Apple's precedent seems to be pull the games immediately from the AppStore and not wait for an update. That being said, it would be extremely strange in a corporate sense to see a fair number of top grossing apps disappear.

Since the apps were approved by the previous terms they still can be sold, i guess... Now if the developer submits an update then it must comply with the new terms...

Approved apps have been pulled before (Google Voice apps) so they could do it. I doubt they would, but it's not without precedent.

Good point, I remeber reading about a game, initially accepted, that had been pulled out because it relied on a library that was able to call private APIs, even though the game didn't use that part of the library.

This happened when Apple started to scan binaries for infringing code.