Ok, my theory for the sixth season of LOST. This isn't a theory for what 'the answers' of the show will entail, since I cheerfully admit that by this point, I haven't a friggin' clue. But this is just a theory as to what the structure of the season will look like and how the makers of the show will tell the story.
"And now, in S5, we've seen....what, exactly? The Island destroyed by a nuke? The timeline changed so Oceanic 815 can continue on its merry way in 2004 and all of the characters' lives will continue as if the crash never happened?
Doubtful. I honestly believe that after hammering home the "what happened, happened" mantra for a full year that the LOST writers would just throw it all away for a continuity-shattering explosion. I believe Miles' theory was the correct one (that activating the nuke into the magnetic energy field was the actual 'Incident'), and that Miles' dialogue was included as a reminder/hint that Jack/Daniel's grand plan wasn't going to actually change anything. There were too many hints left in the final sequence at the Swan that things were proceeding as they had in the past --- Dr. Chang suffered a major arm injury, leading to the prosthetic arm that he had in the Swan's orientation video. Radzinsky's continued life, since he was pretty much the only DHARMA guy that didn't die and we know that his eventual end comes when he commits suicide after a stint at typing in the Swan's number code. And, as well, there are still some loose ends to be tied up back at the Dharma Initiative, like the fate of Horace (who curiously wasn't in the episode), his shady wife Amy and their soon-to-be shady son Ethan."
Sure enough, the big question over the summer has been whether or not the Jughead detonation was successful in changing the timeline. One theory being floated is that Season Six will begin with everyone on Oceanic 815 in 2004, living different lives and not crashing on the island, but they'll eventually start to get memories or (even better) flashbacks of their past lives, suddenly remember the events of the series. and all end up back at the Island somehow to conclude the story once and for all. I'm not a big fan of this theory since it would take at least a few episodes to get everyone up to speed and back in play to head back to the Island.
What I'm instead suggesting is that rather than picking between the 'whatever happened happened' theory or the 'destiny can be changed' theory, we're actually going to see both of these scenarios take place. After the bomb goes off, Jack/Kate/Sawyer/Hurley/Miles/Jin/half-dead Sayid will all be somehow transported (via timeflash, via Jacob's touch, who knows) back to the present-day, where they'll join Sun and company in the aftermath of Ben's murder of Jacob. There, it will be explained to them that their actions did, in fact, cause a change in history and created an alternate reality timeline where Oceanic 815 didn't crash. The catch, however, is that that alternate reality (let's call it Earth-2, for all you DC Comics fans out there) is currently on-going, and the original Earth-1 versions of Jack and company that we've been watching the whole time are now without a reality to call their own.
This is kind of a confusing idea, so let me use a more well-known example. In Back To The Future 2, Biff goes back in time and gives his younger self the sports almanac that young Biff then uses to amass a gambling fortune. When Marty and Doc go back to 1985, they find themselves in the cracked-out 'Hell Valley' that has been created from Biff's rise to power. What's important to note in this example is that Marty and Doc from the original earth didn't cease to exist since Biff had changed the timeline --- they were still there (alongside the 'Hell Valley' versions of themselves) and conscious of what had happened so they could go back in time to fix the problem and restore the original timeline. Jack had presumed that setting off Jughead would kill them all and destroy their entire reality, but no dice --- just as the original Marty and Doc were still around, so are the original Jack, Hurley, Jin, etc.
Something similar happens in, ironically, another JJ Abrams/Damon Lindelof project: the most recent Star Trek movie. Now, neither man wrote the script (they co-produced and Abrams directed), but the basic idea for the film is that a time anomaly sucks Spock and the villain Nero back through time, whereupon Nero kills the father of an infant James Kirk and causes a whole bunch of other problems. However, old Spock doesn't blip out of existence. He explains that his universe (the continuity that Star Trek fans have been following for decades) still exists, but now he and Nero are also alive in this new reality caused by Nero's action. This was rather an elegant way of rebooting the franchise and enabling it to tell new adventures of young Kirk, young Spock, etc. without pissing off the Trekkie fanbase who, if you hadn't heard, are slightly anal about continuity.
So what happens now on LOST? Our Losties are trapped on the Island since (as Richard will likely explain to them), they can't go back to the real world since 'their' real world no longer exists anymore. It wouldn't surprise if the other Others were similarly time-bereft people who no longer had a reality of their own to go back to due to past 'incidents.' The Others' Temple is perhaps a place where these various time disturbances are tracked, which is why Richard always seems on top of everything that's going on. It might also explain why Ben and Charles Widmore had such wealth and power in their off-Island lives --- maybe they usurped the lives of their alternate versions, which in Charles' case, led to his banishment from the Island.
It puts a new spin on the "whatever happened, happened" meme. The LOST characters "happened" --- they lived their lives and caused these events, so the universe can't just blip them out of existence. Of course, this doesn't explain how they survived a close-range atomic bomb blast, but, uh, let's just chalk that one up to....magic? Actually, if the "Jacob's touch" theory is right, then magic isn't a bad guess.
Thus, here is what I think each episode of LOST S6 will look like. The main plotline will follow the story on the Island, and we'll still have character-centric episodes. But the 'flashbacks' won't be flashbacks at all --- they'll be looks at Earth-2, and we'll follow the same character in his/her alternate reality of what their lives would've looked like had the Swan Station never existed and Oceanic 815 hadn't crashed. Given that the series has shown us the many small ways in which these characters' lives have interconnected over the years, it wouldn't shock me if we see some significant changes to their lives before the Oceanic flight even takes place; the ripple effect of that bomb going off could change any number of things. For example, a Kate episode in S6 will center on Kate on the Island, and the 'flashback' will see how Earth-2 Kate handles being thrown in jail or some such adventure.
Lindelof and Cuse have already said that S6 will have echoes of the first season, and this is how I think that will be accomplished. Part of the reason that LOST was so fascinating from the beginning is that every S1 show revealed something new about every character's lives and motivations via the flashbacks. If my theory is correct, this same effect will be achieved in S6 as we learn all sorts of new developments in what are basically new lives of (the Earth-2 versions of) our beloved characters.
I can't wait until Tuesday night so this theory can completely be blown apart in, like, five minutes.
(btw, the image is from this cool page of LOST-themed posters by artist Ty Mattson. Hello, desktop backgrounds!)