On the other hand, we can imagine the Hobus explosion releasing (for whatever reason) a "subspace blast", which would turn every star it eventually reaches into a nova. This way, we can salvage the peculiarity of the Hobus star, the time-scale of the phenomenon, the fact that it is a threat to the entire galaxy, and the actual destruction of the planet Romulus.
Too bad nothing of this is supported in the movie or the comic, of course.![]()
So, what Star Trek II should establish is that the "real" Trek universe has been completely destroyed to reassure the fans that they haven't forgotten about it!