The thing about revealing the Joker’s identity is that no reveal could add anything valuable to his character. The Joker is the Joker, it really doesn’t matter who he used to be. The only dramatic reveal twists that could have any actual story impact for an arch-nemesis is if he’s somehow connected to Bruce Wayne or Joe Chill. And neither of those ideas are really that great. They’ve teased him being some sort of entity, which is an interesting concept, but sounds like something the Joker would make up (which is actually one of my favorite character bits about Ledger’s Joker and Mad Love).

I don’t think stories about who the Joker used to be or his origins are necessarily bad, I think there have been good ones told, but in all of those stories, he’s just a nobody. In Batman ‘89 and Mask of the Phantasm, he’s a nobody thug that gets pushed into chemicals. That’s all that matters. He doesn’t become anyone until he’s the Joker. And even with the Red Hood stuff, he’s literally faceless before he becomes the Joker.

I’m curious about what they do with the reveal, but I don’t really think it’s a good idea to set anything in canon.