You don't get it, I can handle parallel universes, I can't handle getting rid of every character except Peter and replacing them with similar but new characters. All character development of the first three seasons has become irrelevant because we have a new Walter, Olivia, Nina etc., I don't know who these people are and I don't care, Fringe was always about the blue universe, that was the core of the show, introducing the red universe worked because it was connected to the blue one by Peter's kidnapping and it worked because it didn't replace the blue one, in enhanced the story.
With season 4 the writers got rid of the blue universe and that was an unforgivable mistake, because there's no way to fix it at this point, they can't simply have Peter return to the blue universe, that would make all of season 4 so far irrelevant and the writers would have to admit that it was a bad idea from the start, they can't stay in the amber universe because no none cares, is there anyone who isn't waiting for Peter to go home? And if they try to merge the universes by having people "remember" things that's a) cheap (Peter doesn't have to fight for Olivia's love, she remembers it) and b) still not the blue universe, even if Olivia remembers, she's still another Olivia remembering things she never experienced.
The amber universe should have been a two episode arc, by stretching it out over most of season 4 they destroyed the show, better cancel it now. What's the point in keeping it around? It doesn't even have the ratings to justify a renewal.