they really don't have anywhere to go with the villain. they can't have super powered villains, so that disqualifies Clayface, Mr. Freeze, Poison Ivy, Man-Bat, and Killer Croc. The director has said he won't do Penguin, so it leaves few possibilities. Two-face could come back from the dead, Catwoman I think would be a choice of last resort considering the franchises history. I think that it really leaves only the Riddler or one of the many gangs/secret organizations that Batman fought.