Hmmmm...
...so the 'flash sideways' were actually a sort of 'afterworld', created by the lostaways for the lostaways. Gotta wonder, just how many of the other denizens of the 'flash sideways' realm were 'real', or mere 'props'.
So...the island wasn't destroyed, and as I'd figured for a long while now, Hurley was the guy who became the new Guardian. I'd lay odds he held that job for a *long* time (centuries, maybe?). That would explain the radical attitude shift of 'spirit Hurley' in the Flash Sideways - he had a long time to come to terms with himself.
The flash sideways being a sort of afterworld is comparable to some (mostly tribal and ignored) afterworld schemes where spirits take up residence for a while in a world very similiar to the one in which they left. Some Buddhist/hindu type religions feature something vaguely similiar, though my memory is more than a little hazy here.
The flash sideways being an afterworld also explains Widmore and companies reactions in that realm to the lostaways actions there: they *knew* from the start what the flash sideways really was, and wanted to kick back for a while.
Who or what was the 'seed' person/event for the creation of the 'flash sideways' realm? Jack? Hurley? I figure somebody must have 'changed the rules' so that deceased spirits were no longer trapped on the island, but instead had a way out. Probably Hurley. Maybe, though, it had something to do with the water cavern?
Additional thought: who put the plug in the water cavern to start with? And was it ever pulled out before, say at some point during Jacobs long reign? (he seemed to have some idea what was down there).
I *knew* the pilot survived the sub blowing up.
Ok...so a few folks got away on the plane, and a few others remained behind on the island. Not exactly a tidy ending, everybody all split up like that. Did the plane make it back to civilization? Or did it crash (wondering about the fuel situation). Meanwhile, we also end up with a badly battered Desmond *still* stuck on the island, away from his beloved Penny. I have to wonder, given the way he behaved in the Flash Sideways and the way he connected back and forth so readily, just how much time he spent on the island after being pulled out of that cave. Did Hurley try dumping the Guardian job on him later on?
All in all...there might be material enough here for a movie or three, possibly a sequil series...