Fight choreography is the only thing they can improve upon. The rest is not about improvement, it's about doing something different for a different genre, different universe, different version of Batman where everything can be exaggerated. For the grounded universe Nolan had, certain limitations had to be put on his Batman, as well as his villains. Here we have a 20 year career for Bruce under the cowl, meaning more rogues by the dozens have come and gone. A more futuristic sci-fi genre/world means super-powered heroes, crazier gadgets/technology on suits and batmobiles. A more comic book universe means more CG, more exaggeration with the fighting. Let's not forget 3D for the first time, so Batman may feel even larger than life. They will need to up the ante with his intellect in order to match him with these superheroes.