Nolan would never direct Star Wars for the same reason he will never direct a James Bond film. EON and Lucasfilm would never cede control. Every decision he made would have to be approved by committee or based on some sort of decision based on the brand and marketing. Plus its George Lucas story and arena and he wouldn’t want to do someone else’s story. The Dark Knight trilogy was different because not only did Warner’s allow him to do his own thing, but it was a different adaptation of Batman. He wasn’t told to continue Schumacher, or Burton. Its also a project he was passionate about being a fan of the Batman comics, he went out on a limb and pitched it to the studio. I just don’t see him being that interested about Star wars. Also he was able to have free reign because Batman and Robin tarnished and ruined the brand. So anything that was not absolute trash was an improvement leading to the success of Batman Begins.