Y'all sound like you're more knwledgable on this stuff than me...
Wasn't George Lucas' original plan to make 9 Star Wars movies, rather than 6? There were going to be productions of "Episodes 7, 8, & 9" after the "prequel" trilogy of Episodes 1, 2, and 3. At some point he dropped that idea.
Did he ever reveal at least a basic outline of what was supposed to happen in the last 3 chapters?