The point of the alt reality = showing Jack's sacrifice by Scylla

Season 5 built to Jack's choice to erase their lives and "start over"...leading to Season 6 with the multiple time lines. Narratively, we are supposed to think this is two versions, made because of the split. Most people think and have theorized how this fits in...whether it's the ending of the show and Jack sinks the island in the final episode, or several variations of that.

My theory: what we are seeing is NOT the end of the story, and that if Jack and co. sink the island and reset the timeline to the "LA X" version, all we are doing throughout Season 6 is rehashing Season 5.

Season 5, Jack is miserable, and wants things to be reset.

What I think is that throughout the rest of Season 6, Jack learns to accept what the island is, accept his destiny, and that will lead to a choice in the finale: sink the island, destroy everything, resetting the timeline. OR, accept who he is, and accept what happened to him. Become healed emotionally by the journey he has made over 6 seasons.

(Now I'm sure there's other stuff to go along with this...whether it's taking up Jacob's mantle, becoming Adam and Eve with Kate, or becoming master of whatever grand island secret is yet to be revealed.) But the point is, Jack will ultimately make the decision to forgo the "alternate" life he and the others could have had, the safe happy life, in order to realize his destiny and save the island (and perhaps the world).

My two cents...