OK. So I’ve given it a lot of thought and I’ve gone back and forth with many of you in the comments all the while forming new theories. So here goes nothing.
New Theory About Dying
I’d like to put forth this theory: once characters die in one of the timelines they become aware of the other timeline. This would explain Charlie thinking that he had to die and also Juliet knowing that “it worked”. It doesn’t really explain what happened to Sayid. I tend to think that possibly he died in the non-Island timelines, but that seems kinda crazy (maybe Arzt killed him in some sort of racially motivated rage, you saw that look he gave him).
Sub theory. I know I already said that this would explain Charlie thinking he had to die, but I might change that. In 2004 he isn’t dead. So it’ll take a while before he dies and his consciouses merge. The first person to die will be The Marshall, and then Boone soon after. This could be fun if I’m right. (I doubt the redshirts dying will make a difference to my theory.)
Who’s Alive and Where
This is just a list of the people off the Island who are likely dead or alive. And just so you know, I’m staying spoiler free this year. So I know there are a lot of rumours going around about who’s coming back and who isn’t but let’s not post those items here.