Short version:
Peace would be possible if the quarians weren't all warlike vs the geth, the geth are more then willing to return the planet to their 'creators', the quarians however seem to think they have to take it by force.
Long version compiled when reading through the thread:
Actually iirc, the geth are just waiting for their 'creators' to come home, they're just cleaning the place up <<...
Its mostly the quarians (and the rest of the galaxy) that look upon the geth with mistrust, them being ai's & all, and them having defended themselves when the quarians tried to obliterate them.
And i'm fairly certain the geth don't mind moving, they're still working on how to develop the dyson sphere, so i doubt they really are that concerned about resources. (as machines they can go to a remote star with uninhabitable but rich in mineral worlds and strip mine those).
On people talking about major decisions not being able to happen, its the end of shepards story, who knows when the next game will come out, and if it will even be in a timeline thats close enough for our shepard to even be remembered. For all we know they could make the new game closer to first contact, or during the rachni wars, or centuries later.
@Saphra, when a object starts asking questions about souls & purpose of life, you can pretty much put it on the same level as an organic.
@ShadowLordXXX i'm fairly certain it was the quarians themselves who deployed WMD's and wrecked their own planet forcing them to leave it behind (and probably killing off a lot of their own species in the process).
@PhantomSpectre i kind of recall legion saying they are waiting for the creators to return (cleaning it up for when they do), a war is not necessary its just the quarians that think they have to fight to get their planet back.
@Raygereio If you talk to legion he'll let you hear a recording of when a geth questioned it existence and when the quarian he was talking to actually realised sentience was happening (apparently it had been asked before but just ignored, deleted, wiped out).
Theres a difference between having to just blow up a couple million quarians and fighting a race of ai's that (like in bsg) after their body gets destroyed can just hop back to a hub, share its experience and get a new body, not to mention the geth probably have a proper armada compared to the quarians that you can kill mostly by sending 2 dreadnought class ships on their live ships (sad part is that if that were to happen not many people in the galaxy would protest overly much).
On a side note: i blew up the heretics, rewriting them might or might not have worked, they might have reached the same conclusion again.