I forgot about Gotham city sirens! TBH that should be a TV show. As should birds of prey, though they both could work. I do share your fears about tone. Especially if they are turning it into the "Harleyverse" (I know she apparently won't be in sirens or suicide squad 2, but still). Speaking of which, I'm very much looking forward to the Gunn suicide squad. Joker already looks too dark and like they are missing the point, but I hope they prove me wrong.

You can find as many people who worship the Hammill joker as the ledger one. Why can't we try a crazy Hammill type joke on the big screen? Why do they all have to be psychopaths now? The Joker movie isn't even using any of the joker backstory.

It was originally announced as a film starring Margot Robbie in 2016.

At one point I heard it was rumoured to be the second part of a trilogy. The first would be birds of prey with Harley Quinn, the second would be sirens, and the third would be bird's vs sirens.

Right now it's in development limbo. Whether or not it happens could be dependent on performance of birds of prey. And it could be something as simple as Birds of Prey: Gotham City Sirens

Bords of prey

They told about a Batman movie so...

It seems like DC is in a holding pattern, where they are are only greenlighting one by one till they figure out a gameplan. Everything else that they've teased in the last 3 years is in development limbo