I "think" that someone other than Jacob's replacement is going to get off of the island based on this post -So if only one candidate is going to "win" it sort of implies some if not all of the others were going to die.
http://www.arizonasportsfans.com/vb/showpost.php?p=2234637&postcount=433
IMO MIB doesn't need anything physical (ship, plane, sub) to get off of the island. He just needs to make sure that Jacob and any replacement for him is eliminated. At that point, he would be free. Again IMO.Seems like if he was going to save any of them it would have been Lapidus to fly the plane.
When I saw that happening (MIB finding the C4) I thought that they would be idiots to get on the plane for the reason that MIB said. 30,000 ft in the air is a bad place to discover that you missed a brick of C4.They all accepted too easily that Locke said we can't take the plane there may be more C4 on it, the C4 was the size of a brick it would seem pretty easy to find if wanted to look for more but they all just immediately accepted ok lets take the sub.