A Romulan civil war is pretty likely just from the internal forces we see shaking it during that era. And that's not even including things from PIC and the movies, such as Shinzon assassinating the entire senate, and losing the home system to a supernova.
I did have a fun story idea I wrote some paragraphs for a few years ago where the Klingons saw the Enterprise-C go down and the political side of the High Council saw it as a sign that Starfleet was too militarily powerful, and if the Klingons were going to remain a major force they had to strike immediately when the Federation was still a foe they could defeat. So they doctored information about the battle and went to war, but of course the truth came out and immediately imploded the Empire into civil war into multiple divided factions: including one that sided with the Federation and became tightly affiliated. Even getting a lot of Klingons living on Federation worlds.
It all came out of an idea of what would TNG Starfleet look like if that was the time where a lot of Klingon Starfleet officers were beginning to show up in command positions and what their intensely honourable culture would look like in a Federation context. Which I think would have been really cool!