while staying true to the comics, superman existing before makes batman unnecessary in a world with a superman on the big screen imo. he's got super speed, super strength x-ray vision, heat vision, freeze breath. he can do anything. the only way it works on screen is if bats is the mentor, default general. the guy who's been there because, he really doesn't offer much by comparison to the other heroes.
i think they have a great opportunity to make it all work.
i prefer that they leave bats indisposed.
have him show up in a world's finest, then have kal-el go on in search of remnants of krypton/kryptonians, whatever. give him a vacation from earth. he shows up in a JL film.
have the next GL film set in space as well.
Let the flash supplant bats as the terrestrial guardian, "knight" of central city.
introduce wondy and aquaman in a WW VS Aquaman film. have wondy be an ambassador, and have aquaman be the villain fighting from an environmentalist angle. maybe have bats help her out in someway. they settle their differences, become allies and the **** hits the fan for a JL film.