Lucas says hes too old to do Episodes 7-9, but I think most feel the legacy needs to be completed. It is no longer the end of things after Episode VI because we all know there is still more, especially if you've read any of the books that chronicle events after Episode VI.
Many of the future Star Wars books have the original characters in their 40's or older so to me the same actors would play the same characters in episodes 7-9. Those three episodes are the future of things farther down the road, not five years from the end of episode six. What has happened to everyone after 30 years and what do they do when they find ghosts from the past returning to make the final circle complete.
Knights of the Alliance