So as we all know, selecting the Destroy ending with sufficient Effective Military Assets results in the strong implication that Shepard is still alive, to the extent that the LI is telepathically aware of this on the Normandy due to Space Magic.
So, what does everyone think happens? Shepard only takes a final breath before dying? Shepard gets up and waits for someone to find them and finally retires?
Seeing as Shepard is almost certainly not going to be appearing in the next Mass Effect, its up to us what we think happens to our Shepard, at least for now. So what do ya'll think?
Personally, I'm a firm believer that Project Lazarus and the influence of the Crucible extends Shepard's lifespan significantly and there are a whole load of small blue children repopulating the galaxy and pretending to dig for ancient ruins in National Parks, but I am a fan of happy endings.*
PS. If there is already a post on the forums like this, feel free to ignore this. I apologise for cluttering and not being more thorough in my search.
Keep fighting the good fight!
* On an even nerdier scientific note, I don't think this is so implausible. If Project Lazarus is a success, the ramifications for establishing more efficient metabolic pathways and therefore reducing oxidative stress on somatic cells is huge. Would this have the consequence of reducing the rate of telomere shortening? I'm only a High school Biology student, but then who knows with all this space magic going on?
Literal View of things:
-LI 'knows' of Shepard being alive just as Loyalty can affect someone barely surviving a cutscene encounter. That is, the LI has enough hope for Shepard's survival, that they won't accept him being dead. So the Normandy leaves (especially clear in EC) to find him.
-Shepard lives. We can imagine that he dies, and that can apply in our game (the ending was open by design), but the scene itself would only be put there in order to encourage a hope that Shepard survived in some way.
-Shepard may or may not get up. I like to think that the more Renegade Shepard is (and especially the less allies alive and that he's close to), the more likely that he got up out of rubble himself, digging through it, while the more Paragon Shepard is, the more likely that a hand came down to pick up up. The merged version of this would be that Shepard tries to dig out, and ends up more trapped, yet he thankfully arrives at the right spot where allies can find him and pull him out, as he is helped along (doing a walk that is reminiscent of the ME1-ME2 victory walks/struts) by his LI or closest friend/ally.
-In lower EMS, we do not have the hope that Shepard made it. However, we can still imagine he did, if we wish.
-Conversations prior to the ending at least allude to what Shepard may be doing if he survives. He could retire. He could continue to kick ass. Or he could do a form of both. ME3 does include more of a theme of 'legacy' to things, and I wouldn't be surprised to see at least one major location (perhaps N7 related) end up named after Shepard, akin to Grissom Academy.
-I think that Shepard is enough of an augmented person (he isn't 'a synthetic', but synthetic technology was utilized in reconstructing him) that he very well may live on for even more decades than a regular human, though this is left to our imagination. We can imagine Shepard to live a normal lifespan with say, Kaidan/Ashley, or imagine him to last some decades longer than that with Liara (finishing up her Maiden stage at least? perhaps?).
-High EMS versions of all endings (and even 'Low' EMS Control) imply, to various extents, this galaxy's civilization uniting (to at least some more significant extent than before) and advancing past the Reapers' tech wall. Even in Destroy, this may mean that forms of anti-aging technology could be developed. We just have to imagine (thus lines like EC Hackett's 'just imagine what we can do now that they are defeated'). However, it does seem that the Destroy galaxy will advance SLOWER than in Control and Synthesis, keeping things with a much more 'mortal' tone, so I don't at all expect Shepard to live forever, and perhaps not for more centuries. I'm definitely thinking that it is possible that he lives 'safely' past 100 though - something considered more normal for humanity in that century anyway (at least for the wealthy? I forget).
Personal Ideas of things:
-ME3 (and perhaps beyond) was all actually a world in a Reaper that was a reconstruction of memory (of an actual war) and several other major sources, and therefore is its own storyline that runs parallel/contrary to what we'll see in the next game.
-Therefore, the 'Shepard' that 'wakes up' in the ME3 ending is not exactly 'our' Shepard. There was no 'real' Shepard at this point, only the 'one we got'. And whatever wakes up after Destroy isn't 'our Shepard', but as an extended form of the ME1-ME2 change of Shepards (after ME1 Shepard 'died'), we may see 'The Shepard' continue for 'One More Story'. A new, yet optionally old returning protagonist.
-The choice at the ending of this virtual experience determines the composition of a new created Reaper, powered by the 'device you call the Crucible'. The experiment of the Cycles is wiped, and instead of the big colored waves, the 'real world' experiences only a shutdown of the Reaper control signal and a birth of a new Reaper that may be able to encourage the 'new solution' (Destroy/Control/Synthesis) to a wrecked galaxy. That would make ME3 a 'dream', that we can now make into a 'reality'.
-So Destroy has the 'N7' character wake up, and perhaps be customized on whether he remembers Shepard's Journey or not (a lot of optional conditions that doesn't hugely impact the main storyline's progression), and the story of Mass Effect continues. You can endeavor to reconnect with some form of the friends/allies/loves you met, even in a setting that feels strange and alien compared to what you thought was true before.
-Blue babies still possible? Blue babies still possible. Just not as we thought they would be.
You can utterly ignore the 2nd part of this post, but at least the 1st part (Literal) is IMO a pretty good guess at the post-Destroy life for Shepard.