Is it at all possible?
I'm thinking of poor Old Spock stuck in the JJ verse. Is there any way he could ever return to his own time? He can't go to the future because it'll be the future of the JJ verse. But if he goes back to the past, before Nero arrived and then he time traveled again into the future what future would he arrive at????
DS9 had little gizmos that allowed transporters to beam between alternate universes. Perhaps he could build one and beam home.
BUT, Spock doesn't want to go back to his timeline/future. He's at least in part responsible for the destruction of Vulcan, and he's doing his part setting up the new colony (and, apparently, repopulating the species). What's he got to go back to in the prime future? No Romulus, no reunification, no nothing.