[Superman/Batman] Endless Loop

What would happen if Superman were still Superman, still Clark Kent, even Kal-El, but Batman were no longer Batman and was just Bruce Wayne?

Probably a story about [what the old man gets up to with his old buddy after losing his Batman identity, eating and drinking together and fighting monsters again].

I'm obsessed with old-school comics, so my take on Superman and Batman's relationship is closer to the Silver Age idea of them as "best friends and partners," rather than the more common version where they "respect each other but don't agree, stake out their own territory and promise not to trespass, and occasionally get on each other's nerves."

Anyway, some things are just my own invention, though I've tried hard not to mix things up too much. The animated and comic universes are probably all tangled together too. My memory's terrible and my research isn't rigorous, so feel free to call me out [sticks head out to get hit