I'm not sure if it's been mentioned here on the blog lately, because i haven't really sifted through things, but i wanted to put it on here before the airing of this weeks episode.
I'm not sure if anyone recalls the episode "Stranger in a Strange land" from season 3, but it was the one were Jack was locked up and being interrogated by the others, and Isabel (the one referred to as "the sherrif") translated Jack's tattoo which said "He walks among us but is not one of us."
Since Jacob is looking for someone to replace him, it seems like Jack is the most likely candidate to do so. Sayid is "infected," Sawyer is now basically on the same side as the smoke monster, and jin and sun are at the temple where the now "infected" clair is going, and i think she's going to kill everyone. Besides, Jacob's ghost is now catering to really only two candidates in the last episode, Hurley and Jack, and now that Jack is starting to understand his importance after visiting the lighthouse, he may be more understanding and willing to work with Jacob here on out. Hurley's only purpose so far seems to just be a middle man between Jacob and Jack.
Basically my point is Jack seems to be the most likely candidate to follow Jacob. Plus the fact that he's branded with the words "He walks among us but is not one of us" is like saying how he walks around with all the other island dwellers and survivors, but he's not one of them. He's destined to be the new Jacob.
That's what i came up with so far. just an idea to think about.