Hey all,
This is a theory I have had since episode one this season, but haven't bothered to type it up yet... but since I haven't read it anywhere else, I will get it out there quick!
We have been told that the ALT universe is not insignificant, so it needs to have some purpose, but by this point it seems that there are very few ways the two could tie together in what is left of this season. Enter: flash-forward theory.
What we are seeing is NOT an "alternate timeline" that is going on at the same time as the Islands events, but is actually the result of something that will happen at the end of Season 6, meaning that what they are saying is ALT timelines is actually a flashforward to what happens after they were sent back in time for real at the end of season 6.
Jacob and Esau/MIB have a wager going on about how it will "end"... will people destroy/corrupt or will they have some greater end (see season 5 finale opening). My theory is that at the end of season 6 something will happen to send the losties back in time to their original flight, but they will not go back to who they were... who they became on the island will change who they become off the island. We then see them caring for each other off island in new redemptive ways (Jack/John in the airport, Kate caring for Claire, Ben and Locke's apparent new friendship). In that case Jacob ends up being right, people can change and good can come out of them.
What this would mean is that what we are being led to think is an "alternate reality" is actually the true ending to the show, they are giving us flashfowards (that take place in the past in a timeline sense, seeing as it is 2004), but disguising them as an ALT reality! At the end of the show we will be like... "what just happened" until we realize that they have been showing us the true ending all along. This also gives us a whole season to see how the story of our beloved losties ends, and leaves room for one more big twist!
(bonus call: Jack will get cut on the neck just before getting sent back in time. Second bonus call: it will seems like Esau/MIB has won at the end of season 6, until we realize that what we are seeing is a flashforward, and then we realize Jacob had this planned all along!)
Has anyone proposed this theory yet (or something like it)... I would love to read someone else's take on it... can you point me to it? Also, come on, admit it... this is whats going on!