This is from the Shepard Surviving thread. It details my view of how things should take place for the major players post-war, though it does incorporate references to my Shepard.
Fate of the major Galactic Stage Actors and Species;
The alliance = while humanity played a significant part in defeating the Reapers, a massive outcry began against the alliance when knowledge came to light that they had advanced warning of the imminent Reaper arrival and did next to nothing to prepare while obscuring and censuring information at even the highest levels of governance and military command. The issue was exacerbated when a 'posthumous' biography was released about Shepard, where he expressed his extreme dissatisfaction with the alliance, the image they built up around him while censuring and ignoring his warnings, and their general impotence to responding adequately to issues. This tell-all reveal was a blow to alliance propaganda to a significant extent, as many within the alliance considered Shepard to not only be their hero, champion, and savior, but an outright god. Seeing how their own idol felt about the alliance and his own points on why they were flawed (As well as revealing that Shepard was very largely sympathetic to Cerberus), some felt betrayed by their hero's dismissive stance on them, some were stunned that their hero wasn't the paragon of justice and alliance-y-ness that the alliance had touted him to be, and many were forced to realize some inconvenient truths about the alliance and Cerberus. Shepard meanwhile initiated some backroom maneuvering to put the alliance squarely under his control, and using his influence, began reforms of the alliance that made them a much more... progressive but firm organization while hiding the existence of his organization from the galaxy at large (a good example of what they're like is the Empire of the Hand, the Imperial Remnant under the control of Pellaeon, Darth Revan's Sith Empire, or The Fel Empire, all from the Star Wars Expanded Universe). As well, the new home for the Citadel in orbit above Earth ensured that humanity as a whole would become the new political, economic, and military powerhouse for the galaxy. On the hidden side, most Reaper technology and material recovered was by the humans, which was used to further their own technological advancement to a step where they were now at the cutting edge. If humanity was seen as the vociferous upstart race before the Reaper war, their new level of dominance put them at a quantum leap ahead of everyone else. Humanity was seen as not only a key species that was only just entering into a golden age that would see them at the forefront of galactic affairs for eons, but the species that was likely to hold unofficial stewardship over the galaxy for the foreseeable future. We are the giants now.
The Council = The incredible outcry against the Council was immediate. The Turian councilor was killed on the Citadel during the Reapers takeover, while the other two fled. The Asari councilor later made a reappearance, apologizing for her actions and choosing to step down from the role of councilor. The Salarian councilor on the other hand was a bit more practical about his actions, and chose to try and stay in power. He was assassinated within a year. No one knows who killed him. The Council institution as a whole received much demand for reform from almost every species, with large scale riots demanding to know why the Council did nothing to prepare for the Reapers. Eventually, a new council is established, with a significantly increased supranational integrated military command. The Council itself has been permanently relocated to Earth with the Citadel, giving Earth a significant boost in political power, as well as making them the new 'technical owners' of the Citadel, thus ensuring that their presence on the new Council is very formidable.
Cerberus = While still more or less reviled by many, Cerberus reputation improves to a point where they are largely vindicated by history. Much of this is its successor organization's work, with Shepard himself being rumored to have been pro-Cerberus and sympathetic to their goals and motives. Shepard, via his 'posthumous' biography, discussed his feelings on Cerberus and how he came to view the rationality of their actions. His subsequent defense, even when believed dead, was considered a betrayal by some, particularly by former members of the crew within the alliance. Others, who were more in the know about the Commander, were un-surprised by Shepard's sentiments. He was known to be a Machiavellian 'do-whatever-gets-results' kind of person (no matter what the cost was or how immoral or 'wrong' the action was) who was very practical and rational, and, while holding onto his own progressive idealism, did not fetter or bound himself to abstract principles and morality at the expense of physical, tangible goals and the mission. The spirit, the idea of TIM and Cerberus was continued on in the next iteration of the organization.
The Turians = Affected hard by the war, but able to recover and regain their strength, being able to rebuild largely to their former state. They were the race that enjoyed the closest relations with the humans post-war, and continued working, albeit with significantly increased human cooperation, to be a galactic peacekeeping and policing force. The Turians saw their own power and strength boosted, and was the only one of the three traditional council races that ended up in a greater position politically than they had been in. The Turians were still relatively concerned about the continued and exponential leaps and bounds of humanities advancements, but were ironically thrust into a role of placator species that had to reassure others that humans weren't trying to clean house as they were seen as the race that enjoyed the closest relationship with humans and were privy to many of the new technological advancements created by the humans.
The Asari = Hit very hard by the war, as well as having many ancient and unsavory secrets about their history brought to light, there was a large outcry from other species about the Asari and their lack of helpfulness in the war. Being initally unmoved by pleas for a united response to the Reaper threat until it was directly threatening them, as well as being found to have had key information on the Protheans and Reapers hidden away for millennia, the Asari faced many blows to their standing in the eyes of the galaxy (and among their own citizens). While they were able to eventually recover their economic assets and rebuild their worlds, it was soon seen that the Asari's era of prominence over the galaxy had come to an end after several millennia of being the most advanced and dominant. Humanity stepped into the role of most influential race in the galaxy, and they were keen to not make the same mistakes as the Asari. The Asari retained their image as more peaceful arbiters and diplomats, but had a difficult time re-establishing themselves militarily and found their position increasingly marginalized, as much was possible for one of the 4 key races.
The Salarians = Perhaps facing the most negative response of all the Council races, the Salarians were seen as having altogether largely abandoned the war effort despite providing significant military and intelligence support. This was due to the sheer ineptitude of the leadership, with many Salarians themselves rather disgusted by their leaderships antics during the war and preventing the assistance of their power over disconcert with the Krogan genophage cure. Despite Shepard's own feelings on the cure (he only did it because he needed the immediate assistance of the Krogan to facilitate an offer of assistance from the Turians), Shepard was reasonably very upset at the stubborn pettiness of the Salarian dalatrass and her utter inability to see the much larger problem that lay ahead of the Krogan issue. However, the Salarians were able to survive the war largely unscathed; While taking their share of damage from the Reapers, Sur'Kesh was seen as getting off relatively easily (though millions were still killed when the Reapers finally broke through Salarian defenses close to the end of the war). This, combined with the usual Salarian ideology of being rational and unsympathetic to other, more harder hit species, as well as certain leaks of information about their activities, put Salarians in a position where they were arguably the weakest of the old cadre of council races as time wore on, finding themselves, like the Asari before them, in more and more of a sidelined position in favor of the prodigious new rise of humanity.
Other races;
The Volus = gained new and improved abilities to regulate the galactic economy, and was introduced as the newest member species of the Citadel Council, finally enjoying their years of under-appreciated toil. Their large numbers and relative lack of attention for the Reapers meant that while they had, like every other species, been hit hard by the war, the Volus were able to come out of it stronger after the reconstruction period, with many of their colonies intact. The Volus were viewed much the same as they always had been, and, in context with the dramatically changed political landscape that brought the rapid advance and ascension of some races and the turbulent downfall of others, they were quite content with this.
The Elcor = one of the species that suffered heaviest at the Reapers onslaught, the Elcor were considered a species in decline, if not outright endangerment. Their relatively nonviolent disposition, small military, and small numbers meant that, while not being seen as a particularly significant target by the Reapers, what damage had been done to them was critical and catastrophic. Post-war, an expedition of Salarian, Asari, and human scientists and biologists began a program where genetic material was taken from Elcor donors and used to attempt to create an artificially sustainable number of Elcor. However, this program yielded unpromising results, and the future of the Elcor remains uncertain.
The Hanar = The hanar were a species that were able to be overlooked by the Reapers for the most part, while still suffering heavily at their hands. Nearly every colony controlled by the Hanar was attacked by the Reapers, though the Reapers found themselves having difficulty fighting the Hanar in their underwater environment, where it was easier for them to flee and hide. Despite heavy damage to their infrastructure, the Hanar were themselves able to largely avoid the Reapers. Their primary issue was the reestablishment and preservation of the Drell, whose numbers were largely depleted by the war. They came out of the war a little worse for wear, but still strong and able; they were seen as the most likely species to gain a council seat after the Volus had joined.
The Drell = The drell, conversely to the Hanar, were nearly wiped out by the Reapers. Despite having small enough numbers that were sparse enough in size, location, and number as not to lose any off-world population beyond what few were on other worlds, the vast majority of the very small number of Drell in the galaxy were located on Kahje. Kahje was hit hard by the Reapers, and while the Hanar were able to quickly and easily flee into the abyssal depths of their homeworld themselves, on the surface, it was a slaughter. With almost no military to speak of and nowhere to run, with the Drell being trapped on what small islands and artificial structures that dotted the surface, it was a slaughter. The few million Drell that lived on Kahje were almost entirely wiped out to the last, eliminating an irreplaceable gene pool and population reserve. Post-war, it was estimated that there were less than 100,000 Drell in the galaxy. The Hanar once again set about to preserve and protect the Drell, investing largely in genetics and possible cloning to preserve a dying species.
The Krogan = Despite the cure for the genophage and their invaluable assistance in the war, the Krogan were met with icy apprehension that was only exacerbated by their continual penchants for violence and confrontation. As well as learning that the only reason they were cured were so they could be thrown at the Reapers, the Krogan were quickly isolated on a couple of worlds within their home system and were essentially told to control their breeding, learn to play nicely, or face the humans and turian battlegroups in orbit who were ready and waiting to finish the job that had been started. The Krogan were not allowed a military, severe restrictions on weapons research, and enormous levies on travel and trade. The Krogan were understandably bitter about this, though with new progress and change among the younger generation, were relatively quick to realize that they still had an opportunity to grow, just not at the expense of other species. As well, the Krogan also knew that they were in no position to argue, with fleets in orbit that were capable of raining down hellfire onto their world should they misbehave, and a new asteroid that had been towed close to the relay and fitted with thrusters, to send a message that any insubordination on their part would not be tolerated. The mantra given to them was 'clean up your act or else'.
The Vorcha = virtually unchanged culture and status from the Reaper war. Continued their existence as they always had, with little to no change.
The Quarians = Despite having their homeworld back, the Quarians had no real prospects after the war. With limited ability to farm and isolation from the rest of the galaxy, the Quarians faced a catastrophe on their world. The Geth were gone forever all of a sudden, and their fleets were utterly ravaged by the Reapers, having been used largely as bullet sponges for the Crucible through their sheer numbers. With those ships went many of their best and brightest, as well as their leadership: only Admiral Koris survived the war, with Admiral Gerrel, Admiral Raan, and Tali all perishing at the Battle of Earth.
With much of their heavy machinery lost with the destruction of the liveships, the Quarians had the problem of having to use archaic methods of farming by hand that was inefficient and unsuitable for sustaining even the already incredibly small number of Quarians. Cut off from the galaxy by the deactivation of their relay, and no easy way for the survivors to establish communication with the outside galaxy for an extended amount of time, the Quarians that were on Rannoch weren't even certain if there was anybody left alive in the outside galaxy. Facing a famine, the desperate Quarians worked to salvage what little farming equipment they had, and were on the cusp of breakdown when a few surviving Quarian ships returned to Rannoch with some advanced enough technology to help stave off total starvation and exhaustion of available resources. However, the Quarians were not out of the fire - Less than 9 million Quarians had survived the combined war with the Geth and the subsequent battle over Earth. As well, the intervention of the Quarian ships was only a delay of the inevitable. And with a significantly depleted leadership and lack of spaceborne assets, the Quarians were in trouble. Similar to the Elcor and the Drell, the Quarians were considered a race in decline, and, with assistance for them slow and time-consuming given the isolation of their system from the rest of the galaxy, their own insular attitudes that continued to persist even after the war, and the lingering misgivings about the Quarians felt by many races meant that despite their own higher numbers and greater individual prospects than the Drell or Elcor, the Quarians had little allies to call on to assist them. All of these new problems were exacerbated by the continued existence of old ones: the Quarians old issues with immunity and disease continued to pester them, as many individuals had elected to shed their protective suits despite not being anywhere near capable of sustaining themselves. An estimated 200,000 quarians died due to this problem, a significant percentage of their already depleted population. Combined with a low birth rate, all the problems for the Quarians considered, even the most optimistic projections for survival were around 60 - 90 years before the species became unsustainable.
The Collectors = what Collectors were still alive, either still fighting for their Reaper masters or awakened by the Leviathans, were destroyed when the crucible was activated.
The Batarians = with a complete destruction of all Batarian colonies and their home system, there was functionally no real Batarian leadership. Only a single Batarian ship survived the battle of Earth, and that ship was a minor cruiser with no significant leadership for their non-existent military. Technically speaking, a single Batarian Commander was the highest technical authority left for the entire species. However, the Batarians themselves, while losing nearly 90% of their galactic population, were still far from destruction. Due to the large number of individuals living outside the Hegemony upon its destruction, there was still a sizable and sustainable population for the Batarians. With refugees in no real hurry to return to any of their former systems, as well as the utter lack of any real sustainable forces on their homeworld, the Batarians largely left on an exodus for a new world in the Terminus systems, largely leaving their old worlds behind. These worlds were quickly claimed by humanity, and offered to the other races as an informal 'spoils of war'. The remaining Batarians cared little, with an entirely non-existent leadership more concerned with creating a new home than focusing on old grudges that weren't technically their's to begin with. Eventually, the Batarians were able to establish a small sanctum of new colonies and build up a modicum of a fleet that opted to exist within the galactic system, though also in a way were they were largely outside the jurisdiction of the projection of the Citadel force. However, the human organization set up by Shepard continued to keep an active eye on the Batarians, and ensured that they would not become a new enemy or rival to humanity in the future. The Batarians gained a reputation for continued political strife, with new regimes and warlords taking over and causing governments to come and go in the span of weeks and months.
The Geth = completely wiped out upon the activation of the Crucible.
The Leviathans = One of the first goals of Shepard's new organization was to look for any further strongholds or individuals of surviving Leviathans. After a thorough scan of the galaxy using their newly Reaper augmented scanning and surveying technology, they determined that the Leviathans were largely confined to the world they were found on, though the possibility remained open that somewhere else unknown, the Leviathans had more survivors; they may possibly have existed beyond the boundaries of the galaxy itself, on worlds inaccessible to the races of the galaxy, plotting their return on the weakened galaxy now that their ancient foe and predator, the Reapers, had been eternally ended. Despite finding no signs or communication from the Leviathans on their world that they were found on, Shepard took no chances. A battle fleet from Shepard's organization was stationed in orbit over the planet, all mention and records of the planet were destroyed beyond the highly classified information privy to military commanders, all Leviathan orbs that were recovered were destroyed save one that was kept shielded and guarded, and any ship that stumbled upon the system was destroyed with no exceptions, so as to prevent the possibility of the Leviathans ever gaining any useful thralls.
The Raloi = the Raloi, having left the galactic scene upon the Reapers arrival to try and hide, were quickly annihilated when the Reapers weren't fooled by their deception. Most, if not all of the galaxy, didn't care.
The Virtual Aliens = Almost entirely wiped out when the Crucible was activated. Less than a hundred 'survived' due to them being in possession of the bodies of hosts (whose consciousness' were destroyed with the other virtual aliens). These survivors, learning to get used to their new predicament, gathered into a single community in an effort to preserve something of their species. Their community was formed to preserve their species as best as possible, using all information that they could remember to put together a codex on their species, while also assimilating into their new host species. Knowing that for all intents and purposes, they had nothing left but their history, these individuals worked to try and recreate a new artificial environment to sustain themselves and rebuild their species in a virtual world again upon the decay of their bodies, with their consciousness implanted into willing volunteers in the progeny of their host species to create a new cultural group.