I'll be surprised if he George Lucas makes any more Star Wars movies, I know there was a rumour that he was thinking of doing some more but I think I read somewhere recently that he decided that enough is enough. I can't think what direction he could possibly go if he did make more Star Wars movies as all the loose ends have been tied up now with the six Star Wars movies he's made.
Star Wars IV 'A New Hope' is sill easily the best