It's taking them waaay to long to adapt The Killing Joke, Hamill pretty much guaranteed his services whenever it's made. Hamill actually brought up The Killing Joke again during the Arkham City panel like he did several years ago.
Also Conroy and Hamill as their respect characters in TDKR would be perfect. Arguably the most loved and critically acclaimed adaption for Batman with voices by 2 unforgivable Batman and Joker voices.
It would all depend if Conroy could deepen his voice a bit more though to fit TDKR Batman.
Also again, Hamill isn't quitting the Joker, he was misquoted. I can't believe Mark Hamill is going to be 60 this year and Kevin Conroy will be 56. Ugh.