"At one point early on, George Lucas talked of possibly needing nine movies to tell his tale of the Skywalker family. But as he actually worked through the story line, he realized long ago that the story he wanted to tell could naturally be told in six two-hour films. The nine-episode mantra, however, refuses to die...and we realize, never will. But George says that the story he has to tell will be complete in the six films, which can then be viewed as one epic saga. He says that he honestly has no story to tell now beyond the destruction of the second Death Star.
"LucasBooks has always checked with the boss to make sure that none of its projects interferes in any way with anything that he is planning. And while plans can change, rest assured that the wonderful expanded fictional universe enjoyed by so many fans has in no way stomped or trampled on any of George Lucas's prerogatives or options."
Steve Sansweet on the rumored Sequel Series to SW @ Star Wars.com