Well, if you subscribe to the Time travel/ conservation of timeline theory linked on the official thread -
The Kwon's baby would have been a net gain for the timeline, therefore Sun should have died just as Ben's mother died to accommodate the net gain that Ben represented. Jin's death may have satisfied the requirement. The same theory may explain off-island Aaron's apparent handicap. If the on and off-island timelines are moving at different rates (up to 8 years difference? or is it 4? regardless...), then off-island Aaron has the same mental age as on-island Aaron - just a different physical age. And because Aaron was conceived off island, he's not a net gain to the timeline. And if you subscribe to the Island-as-Purgatory theory - We must have an exciting episode coming up for Jin to have redeemed himself and earned his passage to the next life. I was really touched by the conversation between Jin and Sun about him being a different man now vice the man he was before the island. Maybe that's it and he'll die now. This theory could also explain Aaron. His off-island handicap preserves him in a state of innocence.
Either way, I'm hooked.