Unfortunately Charlie proved this theory wrong last season.
I've believed that Jin survives and is still on the island ever since they showed his funeral. It seems too obvious for the show to state that Jin is dead and now they leave us with him with C4 on the freighter. They like their twists too much to make it this predictable.
If Jin does die, it will be something random like he'll get shot in the back as they fly away on the chopper and they are forced to dump the body out of the chopper(and a body/person was shown falling out of a chopper into the ocean in the season preview montage) and that's why Sun's distraught.