Ok, anyone who doesn't care about Lost, or who is not all the way caught up with the show through Season 5, STOP READING NOW!
It's been a few days since the finale, and I still can't figure out how they are going to continue the show. There are a number of different hints on what they are going to do, and even routes they could take. Here's my best guess:
Think of everything in a straight line...
2004: 815 crashes, they have adventures, etc. etc.
Beginning of 2005: Oceanic 6 are rescued, live on the mainland for 3 years
2007/2008 (whichever year it is): Most of the O6 get on Aijira 316 and head back to the island.
Now, this is where it gets a bit complicated. Let's assume the two stories ARE running concurrently, so:
1977: Jack, Kate, Sayid, and Hurley go back to Dharmaville and meet up with Juliet, Miles, Jin, Sawyer, and Faraday. It's no coincidence that the group featuring Sawyer ALSO thinks it's been three years since the O6 left. Because the stories were running concurrently.
2008: Sun, Ben, Lapidus, and "Locke" end up on the island, but at a different time because they actually crashlanded on the island.
So if we assume that adventures of the final were both happening at the same time (big assumption, I know) and we assume that Jacob has something to do with the white flashes that have lead to temporal displacement- then I'm guessing Jacob transports Juliet, Jack, Kate, Sawyer, Jin, Miles, and Hurley back to 2008 just as the nuke is blowing up. My guess is that the opening scene of the Season will feature Jack's eye (exactly the same as Season 1) but when the zoom out, he will be in a nuke crater.
Now, I'm not sure how this affects the future, and what it does to the timeline. For example, is there another version of Jack who got on another version of flight 815 that did land safely in LA? I don't know. But what I do know, is that these characters who meet back up with the other group (Lapidus, Ilana, Bram, etc.) have a massive battle on their hands with Jacob's enemy.
Lastly, I think that there are either two smoke monsters, one white, one black that serve Jacob and Jacob's rival, respectively- OR Jacob and Jacob's rival ARE two smoke monsters. Why do I think there are two? Because Locke, in Season 1, saw a smoke monster and he said it looked like a white light and that it was "beautiful." We never saw what he was looking at, and the other smoke monster has been black and not so beautiful. In fact, one thing we saw it do this year was pull a French dude's arm off, only to drive their whole crew crazy so Roussou murdered all the French folks (including her husband.) Doesn't sound like the black smoke monster is up to any good, does it?
Anyway, that's all I've got on that. Feel free to leave your own theories, or comments. Do we really have to wait eight months?!