Considering Lucas is (sort of) about to start production on a super-ambitious television series that is the equivalent to a one-hour feature-film per week, plus working on the Clone War series, plus supervising the 3D conversion, plus working on Red Tails and possibly batting around Indy V, plus all the other projects and business goings-on he has, there really is no possible way he could start working on a sequel trilogy within the next two or three years. And if its two or three years before he himself could devote any serious work to it, you can be sure that no one except himself would know he was thinking about it--probably not even his family. Something that major wouldn't be disclosed to anyone until it was actual practical to start taking preliminary planning for it.

Also, Lucas is closing in on 70. If he started making plans for a ST today, he would 70 when the first film came out and getting close to 80 by the time it was done. Personally, I'm not even sure he will live that long.

No, Lucas is finished making films. He'll put out more Star Wars shows and some stuff he can sort of watch from a distance. But he would never be able to step back from a ST the way he would with a Clone War television series. It would be a major involvement for him. I personally believe that Lucas' career is basically over and that the 3D re-release is his final farewell before he breaks up Lucasfilm, sells half of his assets to charity, and entrusts his successor(s) to oversee the small remainder of the SW franchise EU for the sake of the fans.