A third possibility is that neither happens. The forums don't rollback, but all the posts from today still have their authors hidden.
This seems the least likely outcome, IMO. Would be too confusing down the line.
Also, no idea how Badspot would set it up so all posts from today wouldn't show up on search with names, without breaking search as a whole. The thing is glitchy as it is. And it makes no sense to retain todays anonymity if you can easily check who it was.
Also consider what happens when people post in the same topics tomorrow? It would be ugly if there were both anonymous and named posts on the same page.