This theory borrows on others I've seen posted about parallel timelines. When Jack set of the bomb, he started a new, alternate timeline with its origin in 1977, but the old one still exists (seen in 2007). In other theories I've read, there's been talk of having to merge the two theories at some point. My thought is that there will be no need for that, because the old timeline - in which MIB kills Jacob - will end in the destruction of the world. "God help us all." MIB doesn't seem to like people. He doesn't want people coming to the island and he kills them off when he can. He may have tried to get Charles to kill off Danielle. Flocke told Richard they were going to have to "deal with" the people who brought him there. His end game is the destruction of the human race.
So in order to save the future, the Losties are going to have to rebuild a new timeline, starting from 1977, and make sure it ends differently. There will be no point in them returning to the present, because there will be nothing left for them to return to.
I'm betting we see young Christian in the past, and Jack and Christian can work out their issues so that Christian never dies of alcoholism in Australia and never becomes a tool of the MIB. I'd also expect Des, Penny, baby Charlie, Aaron, Sun & Jin's baby, and Walt (and possibly older Ellie, Widmore, and Ray Shephard) to arrive back on the island soon. When Flocke figures out what they are doing, maybe he time jumps backward himself, trying to try to stop them.
So in order to save the future, the Losties are going to have to rebuild a new timeline, starting from 1977, and make sure it ends differently. There will be no point in them returning to the present, because there will be nothing left for them to return to.
I'm betting we see young Christian in the past, and Jack and Christian can work out their issues so that Christian never dies of alcoholism in Australia and never becomes a tool of the MIB. I'd also expect Des, Penny, baby Charlie, Aaron, Sun & Jin's baby, and Walt (and possibly older Ellie, Widmore, and Ray Shephard) to arrive back on the island soon. When Flocke figures out what they are doing, maybe he time jumps backward himself, trying to try to stop them.
