First, let's tally up my record for s4.
Now, on to S5!
Obviously, the Burton-grooming-Connor thing is happening. And it's just going to get worse from here on out. Connor's going to build the anomaly generators, etc.
Connor, however, is keeping all this work a secret from everyone, so Matt's still confused about his ultimate target (still assuming Connor is too good-hearted to do anything bad.) Abby, however, starts becoming suspicious because Connor is withdrawing from her and everyone else. Eventually, Matt tells her what Danny told him about Philip being connected to Helen. She confronts Connor about this, but by this time, he's too far under Philip's spell to listen, and sincerely believes that the work he's doing is what's going to save them all--not destroy them.
Matt eventually realizes Connor is his target, and at some point has to make a decision about whether to kill him.
If they play this straight, Connor's actually going to kill Matt instead, and thereby blow up the world with what he's doing for Burton.
If they throw in a twist, Matt's going to either kill Connor, or otherwise prevent him from doing what he's doing, and THAT'S what actually blows up the world. The person responsible for the destruction isn't Burton or Connor--they were actually working on a way to solve the problem, but then Matt got in the way, and boom. Tragedy.
Somewhere along the line, Becker's going to die in some terribly tragic way, either at the hands of Matt or Connor, and that's going to be a catalyst for the endgame.
If they go with the straight play, Matt and/or Becker's deaths and Abby's pleas are finally going to get Connor's head out of his ass, and he's going to be a Big Damn Hero (possibly sacrificing himself in some way)
If they go with the twist, Abby's going to take her revenge on Matt somehow.
If Connor and Abby are both still alive at the end of the series, they're going to try to prevent Armageddon by going back in time themselves.
Also, Ethrick is not gone! Danny's going to find out more about what he's really up to. There are enough big questions there to make that necessary. Still think he's just a B-plot, though.
A few other random, out-there predictions:
-They're going to run into a past version of Helen.
-Caroline's going to come back for one episode.
-Lester might die, possibly while trying to prevent Philip from doing something bad.
-If they have a s6, it's going to be set in either the past or the future, with an all-new cast or just a couple of leftovers.