One more episode to go this season and then just one more season to go!
Here's my theory for how it all ends on Lost:
The whole "the plane never crashes" discussion is a giant red herring. I can't imagine the show's creators would craft a story in which the plane peacefully lands in LA but all the passengers still have terrible lives and horrible problems. They can't possible let stand: Hurley's bad luck, Charlie's heroin addiction, Locke's paralysis, Jack's daddy issues, Sun & Jin's bad marriage and Kate's arrest (okay, I'm fine with that last one!), etc.
The key must be a change before they get on the plane. Who ties the most characters together? He of the white sneakers and bad bedside manner – Dr. Christian Shepard. Save the shephard, save the world! Wait, wrong show.
If Dr. Shepard is a better man, he helps so many of the other characters become better people as well (or at least he doesn't mess them up). Yes, this is a half-formed theory, but it feels right to me. Check out Lostpeida's entry on the good doctor and see if it doesn't somehow feel right to you, too.
So Christian Shepard gets a kick in the pants from a younger Charles Widmore or maybe Smokey straightens him out off-island. I have no idea how they do it, but I think Shepard holds the key. The Losties become better people so when they get on the plane (and they absolutely have to get back on the plane so we can see that terrific airport scene redone) we get to see what their lives should have been like. Then they all land in LA and go to Hugo's house for another Tiki party.