We have seen two realities this season. Which got me thinking back to my old blogs about Real and Imaginary Space/Time. I'd rather not go into all that stuff, though. I'd rather look forward than back.
I said before the Island was the Nexus of Space/Time, and I'm starting to think I was right. I know, the Island is under water in the FST; but if the Island exists in all realities, would sinking it in one be a big deal?
My thinking about all these realities was not really accurate. One of them is not Real while the others are all Imaginary. In a sense, each of them is Real to itself, and from that viewpoint all the others are Imaginary. If the Island, however, is the place where all these realities meet, it's the only place they can overlap. The Island is like a meta-reality. We can call it Alpha Reality.
So let's say the FST is happening, and it's Real from its perspective. The timeline the Losties came from is happening, too, and it's just as Real to itself. But the Island...well, I'd say when one comes to the Island, one sorta merges with it and becomes an Alpha, too. ("Because Jacob chose you, you were trapped on this Island, before you even got here.") Perhaps the things people are "remembering" in the FST from their time on the Island is this Alpha consciousness reaching out. We may see the Losties on the Island start to have conflicting memories from their pasts, as well, since an Alpha consciousness would be like the Island: a place where the memories from all its lifetimes would be able to touch.
So if the Monster is trapped on the Island, he's trapped on it in every timeline at once. Yes, in the FST the Island is under water; but the Island exists across timelines, so this doesn't exactly apply the same way as it would to a regular Island (not that regular Islands can sink...). Would that mean he has to sink the Island in every reality in order for it to sink? Is that what he means when he says he's been trapped for a long time? Did Richard come to the Island in 1867, but in a different timeline, one which he experienced lifetimes ago? Wouldn't that make more sense in light of the fact he described his life as "longer than you can possibly imagine", or Juliet described him as having always been on the Island?
Or does the fact we saw it at the bottom of the ocean mean the FST has to be in the future somehow?