Ending Theory: Alternate Realities Align by MBS9467

I'm basing this somewhat off of another theory I had heard about, so there's not entirely any solid ground behind this, merely a suggestion, but here goes:

In this other theory that I had heard about, it was thought that Jack, in the "alternate reality", as I'll call it (where Desmond is scavenging for all the Oceanic passengers to make them remember), will die. When I heard this, it occurred to me that this might possibly come true, for only thinking about what could happen if it did; If Jack should die in the "alternate reality" where everyone else is alive, well, and slowly remembering all that happened on the island , and in the current reality on the island everyone else should die (Sawyer, Kate, Hugo, etc.), leaving Jack the sole survivor and protector of the island, I theorize that these two separated, opposing, and alternate realities should align, coming together like two pieces of a puzzle, or "yin" and "yang", if you will. In other words, they would become one reality together, where all the characters exist in only one place, unlike how there are currently 2 Kates, Hugos, Sawyers, Jacks, etc., in two different stories, and all events that took place on both the island and back in Los Angeles in the "alternate reality" would coexist, or at least the memories and knowledge of the island would remain, all together in the one and the same reality.

I realize that this is quite loose, maybe a little confusing, and I'm not entirely sure how it would completely lead up to it, but to me it seems like a possibility for the ending.