Large numbers of inbound links would be broken, and traffic coming onto the site from those links would be lost. People would be confused. Some small but vocal number of tropers would pitch hissyfits about the site being RUINED FOREVER and some of them would actually leave. But mostly, we'd be cutting off out nose to spite our face.
Unless all (every single one) the wicks within the wiki were also changed to the new name, it would accomplish very little. Doing that would help some, but it wouldn't make the new name as effective as the old name for quite some time; people would continue to use the name they know when they add it to new pages.
Despite what some others said, it would not be cataclysmic. It would, however, bring no good results and do a great deal of harm.
It would make us into liars. If we have that many external wicks, that means that our word has entered the language. We are just reporting the real name for the phenomenon.
Plus, One-Winged Angel predates the wiki.
Everyone Has An Important Job To Do^ Just because the trope was named after Sephiroth from FF 7 doesn't mean it could NOT have been named something else. There's no "Predating the wiki" for that one. if it did, then that would mean that the name was used to represent the final multi-stage boss form thing for dozens of games out there, when it's merely just the name of a song.
Just saying.
edited 15th Feb '11 8:07:48 AM by DRCEQ

Purely hypothetical question here.
Tropes like "Funny Aneurysm" Moment, One-Winged Angel, and some of the other tropes that are far too entrenched to ever rename.
Lets just say... that we did. We actually went and officially changed the names to something more related to the trope. What would actually happen?