I feel really stupid for posting this, as I feel as though it will definatley have been brought up and shot down at some point, but more than anything, I would like an explanation.
In Season 3's 'Greatest Hits', Desmond tells Charlie that he's had another 'vision' of Claire and Aaron getting into a helicopter and leaving the island, but only if Charlie dies.
Unless Aaron somehow makes it back to the island in Season 6, and him and Claire leave on a helicopter, that leaves me to wonder that either Desmond was wrong (which seems unlikely) or, in fact, Charlie didn't do what was needed for Claire to leave with Aaron (die).
I'm not going out on a limb and saying I think Charlie is definatley alive, I'm just looking for this to be cleared up, as I have been wondering about it for a while.
Another explanation is that Desmond saw Kate in the 'vision' but I can't see how Desmond would get Kate and Claire mixed up.
I have also just wondered, typically right after I'd posted this, that maybe what happened was similar to when Desmond was sure Penny would parachute onto the Island, but it turned out to be Naomi, aparently because Desmond saved Charlie from the arrow to the neck. Maybe the whole 'Charlie drowning' thing didn't go exactly as it was supposed to, and therefore it was Kate that left with Aaron, instead of Claire?