I have to believe that Jin actually dies, because notice how Sun tells her perpetually indignant father that there were
two men responsible for her husband's 'death'...and he's one of them. If it were
just him, then we could safely conjecture that he's still alive on the island, but I don't think she would insinuate that two people are responsible for him getting on Flight 815. My guess is that Keamy remotely detonates the boat, right after the Oceanic Six get off it. There may be some sort of time discrepancy, but there it is. What a

ing militant meathead asshole he is.