It's the Dynamic Duo! Batman and Robin!... and Red Robin and Red Hood and Nightwing and Batwoman and Batgirl and Orphan and Spoiler and Bluebird and Lark and Gotham Girl and Talon and Batwing and Huntress and Azreal and Flamebird and Batcow?
Since when could just anybody do what we trained to do? It makes it all dumb instead of special. Like it doesn't matter anymore.
-Dick Grayson (Batman Inc.)
The chemical bath Joker fell into was apart of a new Lazarus Pit that Ras al-Ghul was forcing Ace Chemicals into making
Bat-mite is actually a "Bat God" who travels throughout the multiverse orchestrating the creation of a Batman in each universe to protect its inhabitants.
Bruce Wayne has always been an inmate of Arkham and all of Batman's stories are just his hallucinations.
He became catatonic after his parents' death and what we read is just his mind trying to process what happens around him through symbolic narratives.
The wildest retcon for me would be akin to the one of Wonder Woman in early Rebirth, but done right : the entirety of King's run happened, down to even its most minute detail. But it is revealed that it was the story of a Bruce from the Dark Multiverse afflicting the real Batman when trapped into it by Barbatos.
It'll probably never happen, but it would be a dream come true for me, to have whatever King is planning to "change Batman for a generation" to be quietly discarded that way.
Mine is that we find out Batman isn't a great detective and that he has been faking it for years and years and years. It's actually O'Day and Simeon Private Investigations that solve all his cases.
I agree kings run is a bad dream and ending like that would be appropriate
Batwing was just a figment of everyone's imagination due to spores being released into the air by Poison Ivy.