I think it would be cool to have the Riddler as the main villian for the next one. I think it would be very interesting if The Riddler actually was only phsyically seen in the movie for around the last ten minutes or so, the rest of his 'appearances' being through clues or voice communications, maybe with a scrambled voice. It would be a nice change of pace after the "IT'S THE JOKER!" movie; his non-presence would add mystery and creepiness, and the big showdown would be a nice release.
They could use some other villians in the film, too. It would be interesting to have it seem like the other villians are working for the Riddler when in actuality they're being unknowingly-played by the Riddler into doing what he wants them to do.
They could use some other villians in the film, too. It would be interesting to have it seem like the other villians are working for the Riddler when in actuality they're being unknowingly-played by the Riddler into doing what he wants them to do.