I submit this as a theory, not necesarily because I think it is what would happen, but because it would put my mind at ease. If the losties in the 70's do actually change things, how would the writers continue the story and not make it as if we had wasted our time for the first five seasons? I believe the way they would have to do it is have them change things yet remember ever thing that that originally happened. What will be difficult for them in season six is learning what happened differently. This is possible because they will be transported to another time and place, but their present will still be their present and their past their past, full of what they did to alter things. i think they will be transported to the island with Locke and crew and will learn that they did in fact change things and yet they have still been brought back to the island through course correction to play out they end game. I! n this scenario, they actually don't remember the future they create because they have never lived it.
As an additional theory, I think this could also explain Locke's "resurrection." He was resurrected the moment they get back to the island, which is the moment the others were sent back. Maybe one of the things they fix is him having to die. this would explain his difference in personality. he would be back again because as soon as flight 316 returns the crew to the 70's that automatically ensures that things will transpire the way they are now. So possibly he wasn't resurected but in the new timeline didn't die, only he remembers dying because what he knows up until his present remains intact.
As an additional theory, I think this could also explain Locke's "resurrection." He was resurrected the moment they get back to the island, which is the moment the others were sent back. Maybe one of the things they fix is him having to die. this would explain his difference in personality. he would be back again because as soon as flight 316 returns the crew to the 70's that automatically ensures that things will transpire the way they are now. So possibly he wasn't resurected but in the new timeline didn't die, only he remembers dying because what he knows up until his present remains intact.
