This is the (theoretical) end! Based on facts from the show and writers by jesse

It clicked in my head yesterday when I was trying to figure out how an alt reality could in any way lead us to an end that they had planned 6 years ago, and how it could possibly be relevant to the story we've been watching for 5 years. In the most recent podcast, Darlton addressed this with "you'll just have to be patient".

Our crash survivors all interacted with each other, came to realize things, made decisions based off these interactions, etc. In the alt timeline, we're seeing similarities to these relationships from the island. Those characters will move forward with their lives, and continue to experience these similarities from the island life (that they don't know of) all leading to something intense. Jughead insured that the plane didn't crash, so something equally as "game changing" will probably happen at the end of the alt timeline that will segue back into the plane crashing in the opposite timeline. Follow?

Jughead = LA X landing
???????? = island crash

∞

The end result of the alt timeline will be the reason for the crash of 815.

Each timeline continues on from each opposing incident, but each incident creates it's alt reality. Each reality depends on the other, because without crashing on the island and detonating jughead, they can't land in LA, so something has to ensure that they always crash so they can always land.

We've all noticed that Jack, in each timeline, seems to have a sense of what's going on, but can't quite put his finger on it. Like he experiences "Deja Vu", but doesn't really believe it.

We all know the writers and Matthew Fox know the end scene. When Damon was asked if we'd already seen this scene, he lit up and refused to entertain the question. My guess is it's the opening scene in season 1, which would make the show a time loop...but now with an alt reality included in the mix, it's a dual time loop(?).

Each timeline continues on with no knowledge of the other...aside from maybe Jack's sense of something missing.

The only thing missing is how an event in 2007 can cause the crash in 2004, but hey, we somehow managed to get back to 1977 to make sure a plane LANDS in 2004, and we all bought into it...so I guess anything can happen.

Sorry for type-o's and run ons...just wanted to crank it out.