It is going to end better then Lost for the simple reason the guys at Fringe actually have experience explaining supernatural crap in a way that sounds somewhat reasonable. Lost never did that, all they did was pile more and more onto the myth.
Peter will turn up in the next season. I don't think he will be written of the show that easy, this isn't a soap opera.
About the Viking burial, i can't believe the writers of the show choose that... I know we have to take everything in the show with a grain of salt, after all most of the stuff is pseudoscience. But come on, a burial at a lake where they put the coffin on fire? Something like that will never happen in today's time, especially in America.
As to the events we saw when Peter was send to the future, that could very well be an alternative future. By Peter going back in time with the knowledge he has of the future he changed things in ways we do not know yet. All the stuff we saw like Walter getting send to jail and Phillip Broyles his weird eye could very well never happen at all.