after seeing the end of the season finale its obvious Sylar survives. i've given this a lot of thought and i came up with this scenario.
Sylar takes both DL and the person who can create illusions powers (i forget her name). after doing that he changes his form to look like Nathan, then theres a scene between Peter and Sylar(in the form of Nathan) where something similar to this happens
(peter sees Nathan)
Peter: I thought you were dead.
Sylar (in Nathans form): No, somehow i survived.
(some "happy" music plays)
(end of scene)
Obviously this scene could be extended or altered in many different ways but basically Sylar is taking Nathans place...permanatly.
If this were to happen that would mean that Sylar would be in the same position as he was in the future episode.
Also it would be possible that Sylar blows up NY using Ted's power. he could easily survive even without regeneration if Ted's power wouldn't blow him up, but instead he just "emits" that energy leaving him completely safe. that would also be how Peter would survive from his explosion.
If all this happened then there would be a nearly identical future as was shown.
let me know what you guys think