Desmond is the key by DaBooty1

After watching Season 5 again, I am pretty convinced that they did not change anything this time around with the hydrogen bomb. I believe they set in motion things that will lead to a change in the next go around.

i think season 6 will mimic season 1 in that the plane will crash on the island again. instead of showing what is going on on the island, (which we already know), this season will be focusing on the players that are working behind the scenes (jacob and his people, and widmore, eloise, richard) to ensure that what we saw at the end of season 5 (jacob's death) doesn't happen again. i think that they will show glimpses of the characters on the island in familiar situations, but there will be differences from what we saw originally, to demonstrate that each character exercises their free will and some decisions aren't always predetermined.

the reason for this, is that Daniel Faraday set in motion a way for things to change this time. i believe that Desmond will be the key to saving them because he is the only one who can actually change things. that is why it was so important for him to get back to the island. I believe that the second time around, desmond will not choose to go on the boat race, therefore he will never crash on the island and never be the one who has to push the button. we saw in season 4 i think it was, that when desmond's consciousness got sent back in time he was making decisions that he wasn't "supposed" to be making (according to eloise). that is because Faraday helped him when he gave him a constant.

the reason why i don't think anything has changed is:

1) Dr. Chang's hand. we know he has a prosthetic hand from the dharma videos, and we watched him injure his hand during the incident.
2) we know that adult charlotte and miles had the exact experience that we witnessed young charlotte and baby miles have (faraday telling charlotte to leave the island and then she gets on the sub during the evacuation; dr. chang sending his wife and baby miles on the sub).
3) eloise remembers shooting her son, which was right before the bomb went off. at the end of season 5, she goes to visit desmond at the hospital after desmond was shot by ben. we never get an explanation as to why she visited desmond, but she does say "for the first time in a long time, i don't know what is going to happen." that is very telling for a lot of reasons. it indicates that everything that happened from 1977 to the present, including the hydrogen bomb going off, had already happened. she is visiting desmond because she knows that he can change things.
4) When Sun shows Richard the picture of all of them in the 1977, Richard says he watched all of them die. He doesn't elaborate on that, but i am assuming he means he saw the explosion.
5) I also dont think anything has changed because it would make absolutely no sense to show us the present (through the sun, lapedis story line back on the island) at the same time as the stuff in 1977 because if they had changed anything, none of that stuff in the present would have happened that way. they would have been showing us that stuff for no reason essentially.


so basically my theory boils down to this... Season 6 will be Desmond doing something off of the island to try and save everyone while the castaways live out what we already saw (with some differences) on the island. the season isn't going to show us things on the island that we have already seen, instead they will show us things that happened on the island that we didn't see the first time around, and then show us familiar scenes playing out differently due to different choices being made. this will culminate with jacob being saved and the castaways getting some kind of redemption.

I also think this theory is supported by Darlton saying that the best way to prepare for season 6 is to watch the first season.