Do you honestly believe that the creators of High School Musical could actually produce a believable sci-fi setting?
You seem to forget Disney gave us classic sci-fi movies like The Black Hole, Tron, etc.
They're also perfectly willing to "go dark", even in their cartoons (Lion King, uncle murders father. Bambi's mother killed by a hunter, etc.
So don't just jump to conclusions. Disney is about making money, and they will figure out how to keep the star wars franchise making money as long as they can.