The next Villian doesn't need to be Catwoman or Penguin or Riddler. These are just gimmick villians if you used them in Nolan's films, these Villians aren't the Direction this movie series is going in. Batman is on the run. Hunted. It's better to find a less known Villian that fits into this story and Nolan's universe.
I'd like to see a story about the Police Hunting down Batman while Gordon at the same time is trying to remove corrupt cops from the Force. A villian or semi bad guy like Hugo Strange could be introduced, who intends to discover who the Batman is or convince other criminals to take on a vigilante role and take down the Dark Knight.