I recently submitted a voice memo to the Fringe Podcast where I posited a theory wherein Peter Bishop would eventually give up on his quest to return to his old Blue Universe timeline. Whether Walters or Walternates efforts will fail to help him or the fates decide to step in or he just plain gives up and decides to accept these new people as his old family; Peter will decide to stay in thsi new Orange Universe timeline.
As further evidence of this I submit the above sneak peek video. In it, the alternate version of Astrid plainly speaks to Walter about his wants and needs and where his heart really lies. Wouldn't it be easier to accept this Peter as someone he could love silencing the heartbreak that has lingered for years? I think it is a subtle clue into the direction the show is taking in relation to Peter. Acceptance and forgiveness are major themes to Fringe and if Walter can accept Peter and forgive himself I think it will pave the way for Peter to stay in this timeline.
Is it time to color Peter orange?