His first had notables like Alec Guiness and Peter Cushing. David Prowse was not really a notable but I doubt that they hired him just to pantomime (he was surprised when his dialogue was overdubbed).
The actors off old are dying off. Christopher Lee is the only notable "new" cast member.
I could see him handing over the directorial reigns again. Sounds like any future films would be like these are largely be shot in a computer. I don't know of many directors who would want to sign on for that. Peter Jackson still likes some location shooting.
Robert Rodriguez? Now that would be a sight. Maybe a script by Quentin Tarantino? He has to be a Star Wars fan. Although he may struggle to make a script with a preferable PG rating. In any case I think Lucas should tell others the story and let them create it with oversight by him.