You could do a black Joker, and now would be the time, instead of later (when you possibly have a white hero, a white Jim Gordon, a white mayor, etc etc). None of us want to see a bunch of “good white folks” trying to take down the one “evil black guy”. But if every race and gender are treated equally, like in this Reeves version. A black Mayor who wants to make a difference. A black Gordon. A white Bruce Wayne. A black Catwoman. Then it doesn’t come off unnatural. Of course, there’s always going to stupid articles written about the white hero taking down the black villain right? It could bring forth some interesting ideas but it could also come down to a simplistic “this movie is racist!”.
Maybe another solo Joker movie with Lakeith’s interpretation would be the best option?