After finishing Jedi, and putting the franchise to bed for a while Lucas didn't give too much thought to the Star Wars universe. It was only when he gave the go ahead for Timothy Zahn to write the first of the expanded Universe books did he really look at the whole thing.
He had stated that it would be a 9 film series, and with that in mind told those who were dealing with the book licences, that no books could be written from 30 years before "A New Hope" as that is the time frame for the first 3 films. He also left a gap after Jedi so that he could do films 7-9.
Subsequently some books have fallen through that time zone, and thus I doubt any films post Jedi will appear. It would be nice to see something, perhaps a trilogy which preceeRAB the New Order series of books.
I'd also suggest that Lucus would really want to be put through the stress and pressure of doing any more films in this series. The last trilogy while being good, were always going to compete with the original trilogy, and that was always going to be difficult to beat. He did a good job, but not as good as the originals.