The Joker appearance is in my mind the touchiest subject. It would be really cool, if this is planned for a trilogy, is to not see Joker at all and just have him stay in the shadows and work with Riddler/whomever else they pull into this. But at some point a non-Ledger Joker is going be needed in a Batman film. Even in only short set-ups through The Batman, this version presented would work well to me; shadowy mastermind pulling strings through direct accomplices and groups of devout thugs throughout the city.