Being a candidate means that one of them is THE ONE who will kill MIB by Baulu

The names written on the wall indicate that they are candidates to kill MIB. One of them is THE ONE who will be able to destroy him but MIB doesn't know which one so he wants all of them dead. Only the numbers,IMO, are some kind of protection so that the MIB cannot kill them himself. That's why the little Jacob kept repeating that Flocke couldn't kill Sawyer. Tha's why, in season 1, when Locke came face to face with the smoke monster, it didn't kill him. It's not that smoke monster didn't want to, it just couldn't. The open door that MIB found was when Locke wanted to kill himself when he was off the island. That's the loophole! The candidates have to WILLINGLY give up their own lives. I think that he will use Sawyer's grief over Juliet in order to make him want to die. I think that at one point, smoke monster will appear as Juliet and asks Sawyer to die so that they can be together forever. Sawyer misses her so ! much that he might just do it. But something will probably stop him. IMO, Sawyer will figure out that this is not Juliet when he'll ask her something that only him and the real Juliet would know about.

Jack will probably turn out to be THE ONE. If it's not him, then my second choice is Hurley.