He wrote scripts for 7-8-9? I don't believe that. Sounds like the same kind of nonsense when Lucas started saying everything was planned from the beginning. A script is a very complicated instrument. I believe he may have notes or a treatment/outline... but I doubt he has a true script. Maybe a kind of Bible guideline to pass on to the new owners.
Maybe some kind of rough draft. He had stuff written for Episodes 1-3 after the OT was finished, it was more like a novel than a book though and the final result was much different than what he originally wrote.
That's why I'm saying not to worry, whatever he already came up with isn't what they're going with, and they're already talking to writers about the project. I would imagine his involvement would be more like his involvement with the books, just approving things that they might want to do with the story if it's something serious.