Fringe will be back on soon....but here is what I wonder.
IF Peter Bishop disappeared and everyone has forgotten him, (in other words he was erased from History) With only the Observers remembering him (Oh I now know who they are) Would this not mean a reset of the two universes thou. First Foe-Livia would not have a kid, so Walternet couldn't get DNA to start the machine...BUT even before that 1st, Walter (From either side) would not even have Peter to save. - The war between the two sides would be over because it would have never started.
So who are the Observers - they are of course the 1st people, but more then that, they know the secret to Walter's time travel experiments, and went back to pre-history, to bury the pieces of the "weapon", The thing they know is that the "boy is important" the boy being Peter Bishop.
I think they can travel different time-lines and see outcomes from differences in each time-line.
Anyways, with out Peter Bishop, the show is over right?