Lucas will never do 7,8,9. The only way 7-9 movies would get made is if Lucas handed the material to a director to shoot the movies, and Lucas could essentially do what he did during ESB, run Lucasfilm, and make sure his story gets told, but someone else tells it. Unfortunately Lucas has gotten so hands on in the movies, that this will never happen as he has even said when Steven Spielberg asked to direct one of the PT movies, "Sorry Steven, SW is my baby."