This will be the TWIST of Lost by James Hughes

Everybody is expecting a twist to Lost, and having Jack become Jacob and be left sitting on a rock with Locke doesn't seem to be what people want. Everybody thinks this is too obvious for Lost. So here is the most likely alternative:

In the 'Lighthouse', Jacob told Hurley that "Jack is here to do something." That implies a singular event. Not a 'becoming' Jacob which is a long transition. By killing Jacob, Locke had found his loophole.

Throughout ALL the seasons it has been made clear to us that there are RULES. War does not have rules, only GAMES. So this is a Game.

Locke can only win 2 ways:
a) He kills all the candidates left on the island so that he can escape. Currently that means Jack, Hurley, and Sawyer will die (Kate is not a candidate anymore)

b) Locke destroys the Island
This points to an original thought of mine and the REAL TWIST of Lost....WE HAVE ALREADY SEEN THE LAST IMAGE. In the season opener we saw the Island at the bottom of the sea....was this the ending as well??

For Jacob to win he needs a 'Candidate' who will do something of FREE WILL to END THE GAME. That is what Jack is being lined up for. We can all speculate on what that action will be, but it will be a singular event, and Jack will recognise it when it comes his way (just as Jacob predicated in the Lighthouse episode)

Remember, the line "the candidates are here to replace me.' would be a huge line, but was NEVER said by Jacob. All he ever told anybody was that he was bringing Candidates to the Island. Illana, Ben, and Locke, all ASSUME that the Candidate is a replacement. But Jacob never said that. He said he would find a replacement, he never said the Candidates would be how he found them. The Candidates are here for something else. They are here to END THE GAME. Can anyone reading this honestly see Locke going back to sitting on a rock after all that has gone on? This is building to a final climax. He just wanted Man in Black to think the Candidates are meant to be Jacob's replacement. But Jacob has been fooling him (and us) the whole time.

That's the twist, there was never going to be a replacement for Jacob, only someone that allows Jacob to win the game, once and for all, and that's the reason Jack is here....