1. We know that many familiar faces are coming back to the show this season (see this poster for reference).
2. Last the night Annoying Asian Dude (aka the AAD) who refused to give the answers we desperately crave told us that Sayid who was once dead, was now corrupted (nice job by the writers having him take a whole episode to do this).
3. Ok here's where I detonate jughead on your faces, so hold on to your minds cause they are about to get blown to pieces.
4. The Man In Black has shown that he has the ability to take over people's body, like he currently has with Locke, did with Alex, Christian, Yemi, etc.
5. I think that Sayid's body has been taken over by the Man In Black force, of course this means I trust AAD. But more importantly, I think that everyone who has ever died on the Island (see point #1) will be coming back in the corrupted form. Yes this includes the new Rouseauifed Claire. This would explain how they have managed to get all the actors back in a way that logical, well at least in Lost logic.
6. So with all these zombies coming back (Damon & Carlton have joked about a zombie season) the only people left to terminate these evil Losties would be our heroic castaways. So basically, we're going to get some real deal conclusions here, uhhh, in the form of a gigantic battle where tons of people on both sides are dying. Some people will opt out of the battle mainly the emo-wuss Sawyer, who will some how reunite with Juliet and die in a cave with her, becoming Adam and Eve. By the way I hope Sawyer becomes Mel Gibson/Liam Neeson Takeified and starts kicking serious ass this season!
PAUSE FOR A POTENTIAL MIND MELT: Some people on the message boards think that Man In Black is actually the good guy and the others who are "bad" guys. This would be nuts but how do we really know which side is which. After all don't all the Losties really want is to go home. Sounds like Locke/MIB in the first episode of the season.
7. Yo, TPG, what's good, how will it end? Oh, no shit, I guess you want to know. I think it will end like this. Jack and Locke will be on a beach all there friends are dead by their hands. They will sit on the beach (this is taken from Jeff Jensen), realize that they can't ever leave and watch a plane crash on the Island. The cycle will begin again.
Notes: I mean I'm a honest guy, so I'm going to honest with you good folks. I don't know how this theory connects the alternate timeline. Then again I don't know how Kate could break free from the cops in a stolen taxi, find a friendly mechanic to cut off her chains, then take the taxi back to Claire, then go to a house, stand up for a stranger, then go to a hospital, then evade arrest either. By the way, last night's episode was not good.