Well why can't there be more than one Batman? I mean, Dick really did earn his role as Batman. I know technically Bruce said "Don't be Batman" but c'mon that's kinda lame. Even though I think Tim and Dick need to be Batman and Robin, Tim really grew into the role and I think they even had Dick say "You were a far better Robin than I ever was." but I do like the idea that Tim's even grown up and is taking on a new ID too. Damien is an annoyin' little shit that needs his ass whipped and then realize that's he's full of it. But I can really see like Bruce coming back as Batman, but taking a more mentoring role, maybe even tackling more cosmic matters with the JLA and Dick being the Batman of Gotham, tackling the day to day crimes and issues. I think in many ways Dick as Batman is far closer to early Bruce/Batman. Batman got too... large. I guess you could say large. Early Batman was Gotham and surrounding areas. But then what the fuck is he doing fighting Darkseid?
"You're out of your element Donnie!"
So... if Dick handles Gotham and surrounding areas and Bruce handles the JLA stuff where its more global and galactic threats, that could work out very well. Or have him OWN the name "Dark Knight", maybe wear some more armor or something, be more of a 'knight" than a "detective" that runs around rooftops in tights and drives a Batmobile.