A side point but the Rannoch arc is great but at the same time I can't help but feel that the Geth as a species were murdered.
EDI states that Legion became an individual at the end, referring to itself as I. But there were thousands of individual Geth active in the 'Legion' hardware platform, for 'Legion' to live all those Geth had to lose their individuality (as simple as they may have been.)
Saving the Geth, or making peace, is the technological equivalent of what the Reapers do to organics. Use individuals to create a new being.
I'm still confused on exactly what "each Geth unit would become its own intelligence" means.
The term "Geth unit" usually refers to a single piece of Geth hardware - a Trooper, a Pyro, etc. But this hardware is just a vehicle, and the more complex the vehicle, the more individual Geth runtimes are required to drive it. IIRC, it requires more runtimes to drive a Prime than it does to drive a Trooper.
This is reflected, again, in the scene in the Normandy war room where Legion is demonstrating how the Reaper upgrades are affecting the Geth. "A single Geth Unit - several networked Units, a single Unit with Reaper Upgrades," etc.
I know it's convenient to think of these vehicles as the Geth, such as when Admiral Xen asks "How did you manage to convince Geth Primes to join our side," but the Geth Primes at that point are powered by sufficient runtimes necessary to drive them. The platform isn't an individual. Legion/Geth VI didn't convince a Geth Prime, instead the runtime drivers were convinced. As far as we have been able to see by what happens within the narrative, there aren't specific runtimes that are designated "Prime Drivers" etc, as opposed to the vehicle being driven by whatever runtimes are available to function collectively. So the idea that a "Prime" is somehow different from a "Trooper" is a bit of an organic distinction.
This becomes a bigger issue when the singularity event hits the Geth at the end of Rannoch. "All Geth Units become individual intelligences." What does that even mean? All runtimes become true AI, or all Geth currently residing with a singular platform become fused together into an individual?
Either way, the results of the singularity event are frightening:
If it's each runtime - we're talking about a series of code that required approximately 1,183 versions of itself to even operate on the level of Legion's intelligence in Mass Effect 2 - it's like saying a singularity event suddenly gifted 1,183 individual brain functions in a human with its own intelligence (it's not a perfect comparison). These are things that cannot function on their own in any appreciable sense suddenly becoming a self-aware being.
If it's each hardware platform - we're talking about the fusion of hundred or thousands of individual processes into a single being. If the Geth valued the uniqueness of each runtime at all, this is...well...it's almost like being melted down into goo and then turned into a Reaper. Yes, a new intelligence emerges, but at the cost of the individual components that were sacrificed to make up the gestalt. Further, the number of runtimes lost per unit is going to vary greatly. For example, is a Trooper with intelligence the equivalent of a Colossus with intelligence? What about the runtimes that were powering, say, Cruisers? Or Carriers? How were they affected during the singularity?
What's worse - all of these newly awakened sentients have a perfect understanding of the world they inhabit and their place within it. They aren't children - they are born into this state post-singularity as effective and functioning adults. Organic-created AI require an education - the Geth sentients apparently do not. They have a perfect understanding of everything that the Geth collective required a collective to understand, and that level of innate intelligence and maturity instantly given is staggering to think about.
The most disturbing aspect of all of this is that idea that these are intelligences that exist without any hardware requirements. Think about that. All organic-created AI require a quantum blue box in order to function. This device allows the software inhabiting it to have the processing power necessary to be an intelligence and not just a VI. It's the hardware as much as the software that allow these AI to be individuals. Even EDI, with Reaper-based code, requires a quantum blue box.
The post-singularity Geth require no hardware requirements to have sentience. The mobile platforms certainly did not have this. Further more, according to the Quarians post-singularity, the Geth are uploading themselves into Quarian enviro-suits. That's the equivalent of downloading an AI into a calculator, or trying to put a human intelligence into the brain of a common housefly. The suit doesn't have anywhere near the hardware requirements necessary for the intelligence to function.
This strongly implies that the Geth are suddenly sentient code, which is something entirely unique within the setting. Every AI we see, including the Reapers, have a hardware requirement in order to function. Code that retains its sentience, intelligence and self-awareness regardless of the hardware it is currently inhabiting is, quite honestly, a horrifying proposition.
As an aside - it confounds me that this is allowed to occur at all. Firstly, why is the only solution that Legion or the Geth/VI will accept, and that failure to allow the Geth to do this means outright war? Is it not possible for the Geth to exist and function as the gestalt intelligence they have been for the past few centuries? The destruction of the Geth megastructure does not seem to have affected the ability to reason for the Geth runtimes Legion freed from the Fighter server (and that itself is another issue of contention). Why is uploading Reaper code to the Geth the only solution that Legion is prepared to accept?
Secondly - I don't understand why Shepard would allow Legion to do this? Think about it this way? If the Asari councilor had said "We are going to augment ourselves with Reaper cybernetics in order to save Thessia," or Major Kirrahe had said "The Salarian Union has agreed to put Reaper implants in our heads to give us a strategic edge," would you have allowed it? Is this not what Cerberus did, and the consequences of that are plainly visible.
Why do we, as players, trust that Legion is telling the truth when it says that it is immune to Reaper corruption because of its "complexity?" The entire Geth collective is currently under Reaper control, and collectively, it's going to be more complex than Legion ever was. The danger of Indoctrination during the War is very, very real, and I'm certain during that period we wouldn't have allowed any organic species to willingly augment themselves with Reaper-based hardware for fear of either Indoctrination or outright control. We wouldn't give it to the Krogan, for example. Or would you?
I am guilty of this as much as the next player. We're made to feel as though killing off the Geth is a terrible thing, and it is, but given the choice of killing off a species that is only intelligent collectively, or allowing that species to augment itself with the technology of the enemy when it has been demonstrated that that technology is capable of corrupting its users (likely causing the downfall of countless previous cycles), a species that is threatening to kill us if we do not allow them to augment themselves with it - that sounds an awful lot like someone currently Indoctrinated forcing my hand to get what they want to me.
And yet...we allow Legion to do this, and then congratulate ourselves on making peace between the Geth and Quarians.
The more I think about the end of the Rannoch arc, the more I despise it. I wish I could have been in the discussion room while this arc was being plotted out - I want to know if these concerns were brought up and then hand-waved away in the name of "It's about the characters, not the science" or if they weren't considered at all.
Either way - post singularity, the Geth as we knew them prior to Rannoch no longer exist. Something entirely new has taken their place.