I am building on *several theories* of others but I have some ideas I would like to add to the discussion. Some of this has been posted and discussed at great lengths already. I am reposting it to try to answer/clarify some questions/concerns that have been raised.
It has been argued by others that:
*Every season of lost has started by showing us how the flashes of each season end. Season 1 flashbacks show how they end up on the beach, Season 2 flashbacks show how Desmond ends up in the hatch, Season 3 flashbacks show who the others are, Season 4 flashforwards show how Jack concludes "We have to go back", the Season 5 time flashes show how Daniel was at the Swan construction site and met Dr. Chang.
*Season 6 will be the same. The first thing we saw was how the season ends. This time there is a new story telling device. Now we are seeing flashforwards of flashbacks. The off island LA X stuff IS NOT an alternate reality created by Jughead. We are seeing the reset timeline that has not been created yet.
*Jack looks older in the season 6 premiere. His hair is longer and grayer than it was in season 1. Well... the poor guy has been through a lot.
*In the same way that Charlotte mumbled about chocolate when she was dying, Juliet talked about coffee and going dutch. Her mind is flashing to another period of time... I think in the off island scenes, we are going to see a lot of character resolutions. Juliet will meet Sawyer, they will flirt with each other, and she will ask him if he would like to go get a cup of coffee.
Basically the idea is that the off island alternate we are seeing right now is going to be the result of what happens on the island this season... not the result of Juliet hitting Jughead.
***I think there is good evidence that we have already seen the end of Lost. The writers are notorious for not letting actors see the script until just hours prior to filming. Since they are currently filming episode 12, that means none of the actors should know the final scene... except for Matthew Fox, of course, who has said the show ends in "an incredibly powerful, very sad and beautiful way. I think is going to be pretty awesome." He knows what the final scene will be because he has already filmed it. And we have already seen it.
What I want to add to this theory is this: I think I know how Jack will reset everything AND how the island ends up at the bottom of the ocean.
We know this is the final season and the writers have promised us that all of the major questions that are important to the characters will be answered. One major question that is of obvious importance to the Losties is how the island can move through both time and space.
I predict that at some point in this season, probably somewhere around episode 12-14, Jack will learn what the island is and how it can be moved and the nature of time travel. In the mean time, I predict many of the characters on Lost will die. In fact, I would not be surprised if by the end Jack is the only one still living.
I predict that Jack, the man obsessed with fixing everything all the time, will come to the conclusion that blowing up the swan's pocket of energy was not sufficient to change everything. I predict the major battle we are all predicting for season 6 between "Good" and "Evil" will involve Jack deciding that the island itself has to be destroyed.
In the season finally Jack is going to move the island. This time he will move it to a place where it can't possibly cause 815 to crash. He will move it to the bottom of the ocean (space) and at some point around 1970 (time).
This explains why the island was at the bottom of the ocean, yet everything seemed to be basically normal there. It didn't look like a nuke had exploded. It didn't look like a volcano had erupted. It simply looks like it ended up there. I think this is the most compelling evidence that Jughead did not cause the island to sink. We saw the island underwater. There was NO evidence that anything as destructive as a hydrogen bomb exploding and physically sinking an island has ever happened.
I predict it was placed there around 1970 because I think Ben will be seen off island, which means he never made it to the island in 1973. Yet Dharmaville was seen, so it was moved to a period in time after The Dharma Initiative arrived.
Because Jack moves the island to the ocean floor at this point in time, all of the people Jack cares for will be saved, including Juliet since she will never go to the island. Heck, he might even realize he can save Ben by ensuring he never goes there and is never shot by Sayid. What if Ben turns out to be a decent guy when we meet him off island?
I predict the show is going to end with Jack, who's neck was scratched up in the final battle, on Flight 815 headed to LAX. At this point, I think Jack remembers everything that happened. That is why he was frightened this time at the turbulance, That is why he was looking at everyone so curiously and why he looked confused when we first saw him. I think he asked Desmond if he knew him simply to try to gauge whether or not he was the only one who remembers what happened.
This is also why Jack told Locke, "Nothing is irreversible."
The off island flashes we see this season will turn out to be the true ending of Lost. Everything else is just progress.
****ADDITIONAL EDITS & ANSWERS****
I want to add more information to this theory to try to "flesh it out" a little more in order to answer what I think is happening and to address some of the questions/concerns that have been raised by other people.
1) But aren't we seeing two "parallel universes"? I think that is precisely what the writers want us to think. They want us to think we are seeing two "alternate realities" so we won't consider the possibility that we are looking at two different periods in time, instead. Let's face it, this would not be LOST if they were showing us exactly what we think we are seeing. They are going to show us a lot of strange things off-island this season that will leave us scratching our heads in wonder if we stay with the belief that there are two parallel realities created by Jughead.
2) Juliet wanted to tell Sawyer "it worked". That is correct. But she prefaced this by saying, "I have to tell you something. It's really, really important". I believe this is both a clue and a red herring wrapped up in one. They want us to believe that it happened... meaning Jughead. I do not believe IT has happened yet, though. When IT happens, IT will work. Juliet wanted to tell him this so that he would know IT when he sees IT. Unfortunately, she never had the chance to explain what IT is.
3) But Jack seemed so confused and upset that Christian's coffin wasn't on the plane. Well, if you had been through everything that Jack has been through just to get to this point and find out his body was never on the plane to begin with, wouldn't you be upset, also?
4) But the writers have said there won't be any more time travel, flashforwards or flashbacks. Well there are two ways to answer this concern. One, so what? They told us there would never be time travel on Lost and we saw how that panned out. The second, more complicated way to answer it is to verify it. Technically, my theory doesn't involve any of these things. There is only one timeline here... Jack's present and his future. No time travel involved... the island will be moved in time, not Jack. It is technically not a flashback or flashforward, either, since we are seeing a future that will happen in a past that doesn't exist yet. There are flashes happening, but they aren't simply flashing forward or backward.
5) But what about MIB, Jacob, Hurley's new found luck, etc? I don't know. There are still tons of mysteries left for the writers to clarify. My theory is really just meant to explain why I think the island was underwater and what we are seeing happen off-island this season.
6) If this theory is true, wouldn't that mean that all of the character growth we have seen over the last few years will be LOST? (Sorry, couldn't help myself) Well anyway, there are a few ways to look at this. For all of us avid fans who pay close attention to this stuff, we know the first script for the show was called "The Circle". They changed that early on while still in development.
If it turns out that all of the growth we have seen over the years is lost then I guess we have seen the characters come full circle and are right back to where they started. I guess that could explain the original title for the series.
I, however, do not think this will be the way they end Lost. I am predicting at this point that Jack will have some Jacob-like ability to touch the people he cares about and bring some resolution to their lives. This could happen in various ways. Just imagine if you knew someone for three years, then you went back in time and met them all over again but this time you knew three years worth of information about them and yet they think you are a complete stranger. You could do and say some very strange things that could have profound impacts on them. We have already seen him touch and affect the lives of three of his friends - Charlie (saved his life), Kate (stole Jack's pen and used it to escape), and Locke (gave him hope).
It is also possible that we will see Jack develop actual abilities that are more closely related to the strange happenings on the island. I believe at this point we will see Jack crossing paths with all of the people from the island. If you see these interactions from the point of view that it is just an "alternate reality" then many of these actions and interactions are going to come across as truly strange behavior that will fit right into the LOST mythos. However, I predict that if you look at them from the point of view that he is "fixing" the lives of his friends then everything will make more sense.
This way we can have our cake and eat it, too. We get to see the epic battle between good and evil take place on the island, many people we know will die, and then Jack fixes everything. He is, afterall, the guy who is obsessed with fixing everything.
*** This theory (or parts of it) may be completely flushed down toilet on Tuesday night. If so, I look forward to trying to pick up the pieces on Wednesday morning and continuing my obsession with a new theory.