I think you gotta be realistic about it. I don't see Nolan wanting Depp. It may sound perfect, but thats exactly why nolan wouldnt pick him.
Seems like people speculate like Joel Schumacher is making this thing.
I really dont suspect a huge name in this. Nolan likes classically trained actors with a cult following like Bale, Oldman, Cain, Freeman, even Ledger wasnt that big. Decaprio worked, but i am not so sure Depp would. To be honest I havent been all that impressed with Depps films after the 1st Pirates.
I honestly think this movie will take a step back, and be more like Begins as a dark, noir type of gritty pulp type of atmosphere. It wont touch Dark Knight, but hardcore fans will luv it.