I'm very skeptical on WB lowering their standards after Joker has essentially become the most prestigious role in cinematic history.
I don't know, they struck gold, twice with joker... to go for a third win could be seen as... arrogant??
I, as I have said before, would just like a villain that no one likes - it makes your skin crawl.. the things he does, vile. Less is more, we can just see the after match of his gruesome techniques - the damage he does around the city. Seven, Silence of the lambs, Mister Babadook, just nightmarish stuff. I don't want the joker to be iconic, a star in the movie, I just want him to be pure evil.
It could also be a situation where batman has been tracking the joker, then they finally meet and its all played out over one night and boom, gone.. locked away. It could be cat and mouse, with bruce working on it for a whole sequel as a sub plot, that could be cool, like a massive board of clues in the cave, so that, in the third, he gets him and then, it all goes off.
I would prefer its hat way, because, in reality, batman would Never let him get away or not subdue/kill him.