Luke goes to the dark side (which would actually be great I think, I could really see an evil Mark Hamill) and the final 3 episodes are about his journey to bring unity to the force. To unite the dark and light sides of the force. The special one that the jedi's have been waiting for all this time according to their prophecy.
As for the number of films. Even when I was very little, everyone always knew there were going to be 9 films. Everybody was annoyed when George said he was going to make the first 3 because everyone wanted to know what happens next, but then George didn't even make the first 3 films either and everyone gave up on it!
The story with the films was that originally there were going to be 12! Then George decided that 3 of the films were incidental to the story. Since then there were always going to be 9 films. However George claimed he was never going to make any of them. He has however gone back on that and made the first 3 after all. All this stuff about it originally being only one film that Gary Kurtz has been putting about, is not true, there were going to be 12 films, at least by the time star wars was being shot.
Basically the thing about George is he doesn't actually like making films, or at least not directing them. I guess he thought he liked directing them first but then he went off it. However, paradoxically he apparently also sees starwars as his babies and won't let spielberg direct a star wars
The is another intesting idea tho, and that is the stuff that Mark Hamill has come out with recently. Now I'm never quite sure when Mark is just having a little joke but I really believe what he said about telling Mark that the last 3 films would come out in 2011. Especially as he said he expected the first 3 films to follow on quite soon after the original trilogy which was what everyone expected. Maybe George has finally got around to making the first 3 films because he needed to before he could make the last 3.
I can also imagine that George might want to keep it a secret that he wasn't going to make the last 3 films till the early 21st C. I mean can you imagine trying to tell people that! All those kids who want to know what happens next and you won't tell them till 2011! It's also exactly the kind of thing that George would do isn't it?