The REAL purpose of the flash sideways.
So far from what we’ve seen in the flash sideways, everything seems to be going quite well for everyone (apart from Kate). Some have speculated that the flash sideways could actually be the ENDING of the show, after this war is over and the losties get to turn back time and change what happened and live happily ever after.
But i think the writers are lulling us into a false sense of security.
I think the writers are using a very clever plot device, which will confirm just how high the stakes really are.
The losties have constantly been told how important it is that they are on the island, and how important the island is itself.
The losties planned to use that bomb to change the past so they never came to the island, and i think this flash sideways is showing us a world where they didn’t, but its not as sweet as it seems.
I think in this flash sideways we’re going to see what would/would’ve happened if the islands magical magicness didn’t exist (whether its because of the bomb, or i suspect something else) and the losties never came to the island, and i think its going to end in catastrophe. Whatever the island is, i believe it is extremely important in ways we have yet to find out, and i suspect in a world where its power ceases to exist, and the events we have seen didn’t play out, something very very bad is going to happen. The very thing they are all there to prevent in the first place.
So, i think the sideways flash is a sort of ‘what if’ scenario for the viewers to see just how crucial the events of the past 5 seasons really are. We’ll get to see this all play out. Its a clever way to show us this disastrous event, without it actually happening to our losties.
This isn’t a theory, just my feelings on where the sideways flashes are heading.