I don't see Bane or Poison Ivy in the the next one, they don't seem to match the universe created, as no one seems to have actual powers.
I heard originally that the dude that was going to expose Bruce as Batman is the last one could be playing riddler
My personal choice by a country mile would be David Tennant:
As for other villians, they did make out that Joker was meant to be back, I don't think he should be re-cast, but having Harley Quinn in there could be all kinds of awesome, who to play her though is a different kettle of fish, I'm thinking someone like Britney Murphy.
Other potentials are the usual suspects like Hoffman for Penguin (Phillip-Seymour not Dustin)
There's always a danger that they might try to bring in Robin (dear god no!)
Catwomen?