Lets play a game, lets predict how Lost will end. My money is on the black smoke, disguised as John Locke, will get off the island and everyone will die, everyone. At least that's what would happen if I was granted my wish of Martin Scorsese directing this show. How amazing would that be?
I am fairly certain that Jack Shepard saves the world (by keeping smokin aces on the island or kills him, is that possible? with the help of Jacob, is that possible?)
Claire and Kate end up killing each other, because they are no longer on the list, hence, no longer safe and Claire is pretty pissed about Aaron, and they can't all live, they just can't, so in my theory only a few people get to live.
Sayid is crazy and he will die either fighting Whitmore or someone else, maybe himself? Hurley will live no matter what, because lets face it, they won't kill the lovable tub. Sun and Jin will get to leave the island because their life is off the island, with their daughter. Finally Jack and Sawyer will fight each other and I am fairly certain that Jack will finally rip Sawyers beating heart from his chest and fry it up with some nice fava beans.