Romulans would be more of a threat than ever before. Do consider that they are a aggressive arrogant race to begin with: when word has reached their planet that their sun is going to go super nova, the campaign for expansion has switched from ego tripping careers to a necessity for survival of the Romulan Empire.
I'm still kind of dumbfounded as to why STID completely shelved the Romulans even though all the problems in this movie was a direct response to a catastrophic Romulan attack. I know Nero said he didn't speak for the Empire, but the Klingons have never destroyed an entire planet before, and they were also attacked by the Romulans in the same movie. So to shift the focus to the Klingons and ONLY the Klingons seems really out of place.