Well Bruce could still return as a superhero... just not as Batman. I mean let's be honest, after all he could just pass the torch to Dick and Damien. And be more the Dark Knight or something. I'd think after getting bounced through time and space essentially, he'd want a break... or would take on a more... mythological role.
I mean Dick's great with the more down to Earth, Gotham based stuff... while I think Bruce has evolved to be a more... galactic level super-hero. I mean this is a guy who used to hang with the big guns of the DCU. Fuckin' shot Darkseid! This is not the same Batman who prowls rooftops and schtup's Catwomen.