I don't think this would end well. The fact that some many people rally behind Star Wars despite all of the problems they have is part of the problem, and why I think the quality of the prequels was so badly lacking in so many areas.
Also I'll be honest in saying that while he might be thinking of this, it would require him to make another move against people he sold the continuity to yet again. Right now we have at least *3* versions of the future of the Star Wars universe all of which were canon when he sold the rights. We have the young adult books future "Glove Of Darth Vader" and the like which involved the Grand Moffs putting an imposter "heir" of Papaltines on the throne as a new Emperor, We have the "Expanded Universe", and we have the "Dark Horse Comics" future.
A lot of this stuff is absolutly horrendous as well, written by people who have no idea how the universe is supposed to work, yet someone were able to write canon. While popular with some of the fans the whole "Yu'zan Vong" plotline is a good example of something created and written by people who literally didn't have the first clue about the nature of the Star Wars universe or how things work.
That is to say that the universe works in cycles. Good gets a chance to rule, followed by a period of balance, and then a period of evil. The Force dictates these cycles. This is why the Sith in the prequels were so powerful seeming, and why the Jedi found the Force was "cloudy" for them. This was literally an assasination as it was time for the reign of good to end. Anakin was the harbinger of the balance, and Papaltine made the mistake of thinking that he was going to get to rule the new era of evil, when in reality he missed out on the whole "balance" aspect of things.
The idea of Force invisible aliens and things like that miss the entire point of how the universe is supposed to work.
At any rate, the only real way that a sequel could be done at this point is if it was set so far in the future that it was time for the new reign of evil to end. You'd see how all of the things from the original triology went bad in the long run, and you'd have Sith ruling the univese, only to find The Force turn cloudy for them and these "Jedi" guys who they barely remember from the distant past coming out of nowhere and start whooping up on them big time.
The problem with doing that though is of course legal. It comes down to contracts, and quite possibily if the legal system is going to allow George Lucas to violate his own agreements again to gain control of his continuity, since really it can be argued he doesn't own the rights to the future of the Star Wars universe anymore, no matter how far ahead he sets things. So far he has sold those rights three times... right up there with the con artists who sold the Eiffel Tower twice.
I believe this is why he said back when the Prequels came out that he would probably never tough sequels (although he never explained himself). If he really is thinking about doing it, it means that he's obviously got some kind of legal angle he wants to push I'd think.
