Separately, Christopher Nolan confirmed what a lot of people expected, that this will be his last Batman film. And Christian Bale seems to have no interest in making one without Nolan. Presumably, Warner Bros. will keep making them as long as they're profitable, let's just hope we don't get another Joel Schumacher.
After The Scarecrow, Ra's Al Ghul, The Joker, and Two-Face, who should be Batman's next enemy in the Batman Begins/The Dark Knight series? Well, as of now we know that Tom Hardy will play Bane and Anne Hathaway will play Catwoman.
Check out the master list for all the villains covered. I've pretty much run out by now. Obviously, there are more Batman villains, but not any of significance that I know of. As of February 2009, no one is confirmed as a villain. Not the Johnny Depp Riddler, not Phillip Seymour Hoffman Penguin, nobody.