I think David fincher, alfonso cuaron and possibly a peaul greengrass or darren arsnofsky would be suitable if not Nolan
No Paul Greengrass unless someone buys this man a fucking tripod! Seriously, I got way too sick of all the shaky-cam gimmicks in The Bourne Ultimatum.
I can easily picture Johnny Depp as a replacement Joker but I think they'd have to wait another movie for that. I'd be more interested in using Harley Quinn as a way to keep the Joker's presence in the movie without doing an actual recast.
And while I know some people think that the Lazarus Pit doesn't fit in with Nolan's realistic aesthetic, I don't think that this franchise is finished with Ra's Al-Ghul yet. In fact, towards the end of The Dark Knight,
I kept expecting Ra's Al-Ghul to show up just to say to Bruce, "I told you so."