Who knows where they will take it, but there are many things one could do. The most obvious would be to invert the first one where rather than being put upon and spiral downward, we see how Arthur reacts to being "famous" and having a certain amount of power. Does he go full-on serial killer/chaos agent? Does he strike against society to become a genuine super-villain? Or will he find he wants to lead a more "normal, happy life" once given a bit more opportunity but his demons won't let him? etc...
I still think it'd be fun if he ended up fighting a messed up teenager with a lot of eye makeup dressed like a bat. You know the one... (I don't imagine an epic showdown, more like a school-yard fight. I would enjoy that.)