allright how about that :
in the end most characters die except for maybe one or two. Those remaining two or one charcters get the chance (somehow, maybe through that old lady mixed in with the whole time travel thing) to relive their lives as if the airplane never crashed and to have everyones most wanted wish granted. The remaining character(s) accepts the deal as it will bring back to life all the others. We then realize that this life is actually what this season's alternate timeline was all about. The charcaters are back to life, the plane didnt crash and they have one of their most wanted wishes granted : Desmond has the approval or Richmore, Jack has a son, Sawyer is a cop who stops con artists like the one whos responsible for his parents deaths, sun and jin are free from sun's father and together, etc.  Except like we saw an episode or two ago, Desmond and Charlie and all start to remember that they once were on the island, before that "deal". If this theory is true than itll probably end with all the characters reuniting and saying somethign liek "we have to go back".
what do you guys think ?