The history of Lost is the history of its characters being scattered, brought together, re-scattered, re-brought together, re-scattered, etc. Season 5, of course, had the various Lostaways scattered more than ever, separated not just by space but by 30 years of time—and that’s not even counting Desmond, out in a separate orbit of his own.
Presumably, with one season left to go, the main cast has to get back together in the same time and place somehow. I can’t imagine the show reaching dramatic resolution otherwise. So how does the gang get back together? Where do 1977 and 2007 meet? Where, when and how does Desmond get back into the action? And will there finally be a role for Walt in all of this?
I can think of several possibilities, none necessarily good/plausible:
* The nuclear explosion does in fact change time, in such a way that the Oceanic 815 survivors are now, instead, Ajira 316 survivors
* As a corollary: the change in time un-kills all or some of the 815 victims who died over the course of the series
* The explosion doesn’t change any events—Oceanic 815 still happened, etc.—but it gives the 1977 Losties one final kick forward in time, where they find themselves among the Ajira survivors for the series’ climax
* The explosion changes nothing, and no one gets moved in time. Why did I assume they had to get reunited at all?
* Your much better theory here.