Though Batman the Dark Knight is still in production it seems there’s already talk of what villains can be expected in Batman 3. At Cinema Blend a reliable source has said, “Word is that Heath Ledger could be coming back in the next sequel which will have Two Face as the main villain.”
As it’s possible that the Joker will survive in The Dark Knight to make his return and along side him the inside source says “it could also include a certain female feline as well.” The female feline of course is Catwoman, but it must be said that the Batman 3 script is not yet written and this talk is in it’s beginning stages. But perhaps at the end of Dark Knight we’ll have some hints of Catwoman’s possible future.
Bear in mind that the script for Batman 3 hasn’t been written yet, so it’s all just talk at this stage. But if this really is something Nolan is kicking around for a future Batman project, then don’t be surprised to see a few hints at the future arrival of Catwoman in The Dark Knight.