When asked about the direction that the script is going in, Roven said "The creative driver of the project at this point is Chris [Nolan]. There's really nothing more for me to say about that. When he feels that he's got something to talk about, then we'll be able to talk about it." Asked whether or not he knew who the villain would be, even if he couldn't discuss it, Roven smiled and laughed "I really don't want to talk about that project right now."
Not exactly a denial about whether he knows or not, so it certainly seems possible that Nolan and writer David Goyer have a villain already in mind. And just as importantly, it confirms that a sequel to The Dark Knight is in the works. So, let the speculation about who the villain would be, and who will play said villain, begin!
The Dark Knight was released July 18th, 2008 and stars Christian Bale, Heath Ledger, Aaron Eckhart, Michael Caine, Maggie Gyllenhaal, Gary Oldman, Morgan Freeman, Monique Gabriela Curnen. The film is directed by Christopher Nolan.