Cast 'The Dark Knight Returns' (Nolanverse)

[Havok]

So Jenn and I were babbling about stuff and I brought up that I thought that the Nicholson Joker and the Ledger Joker aren't all that different. They both just want to create chaos. She disagreed.

Anyway, I said "Oh man! You know what would be cool? Nicholson reprising Leder's Joker, but in the setting of Frank Miller's The Dark Knight Returns!" And she was all like, "Man, that would be cool!". Then we congratulated ourselves with coming up with such a cool idea and then got some Starbucks.

But I was thinking... Nolan doing TDKR would be actually pretty fucking sweet and would fit into his universe and style nicely.
But who actually would be a good to cast? The mains? The secondaries? And do you alter the setting? The time frame? (i.e. Regan as Prez?) You would have to to make it fit as far as the character's ages go.

So how would you do this?