Now hold on a second, What exactly is the game here - that Jacob is trying to prove? Is he looking for good people period, or good people to replace him? Because if he finds someone to replace him that is good enough, does that mean that by winning he dies?
Or if they're both trapped there, is this why MIB is trying to prove him wrong? So if he dies with no proper replacement (or all the replacements being dead or off the island) then thats the only way he can escape?
If it's so crazy hard to find the replacements, then maybe Jake and MIB ARE the original protectors of the island?
Think about it, if they were just replacements for people before them, i dont think theyd be having this great debate about being proved wrong. Because, um, their predecessors found them right?