This shouldn't be that complicated.
All Disney need do: Get away from the Skywalker era. The sequel trilogy is...not great, but it doesn't really do any permanent damage to the Star Wars universe, other than leaving a bad taste in the mouth due to poor storytelling. The film audience is tired; we were dragged through three films with no designed, overarching narrative and have found the content lacking.
I love the original trilogy, but Ford and Hamil are done. Morbid, but: Hamil will probably barely survive whatever is created/released next and Ford won't, unfortunately. Luke/AI Leia/(maybe AI) Han don't need to appear in new stories. Any film ideas involving the principals in episodes 4-6 should be immediately ignored- these aren't practical. On a similar note, Heir to the Empire, unfortunately, will never happen, given the existence of a "canon" Thrawn, after Rebels, Ahsoka and whatever I'm forgetting.
As others have mentioned, you can't "decanonize" without confusing the general audience and risking further disengagement. This isn't DC: champion (ha) of reboot/multiple continuity mess. There is no Star Wars "multiverse." It's all connected and will continue to be so - but, this isn't really a big deal.
It would be pretty easy to simply move on. Produce a 3-part Old Republic series of films over six to eight years. Hell, develop a canon Revan series - the story is already written. Promote it as, "Before The Empire, before The Skywalker Legacy...an even longer time ago in a galaxy far, far away..." Get people interested again: It's something new, not another "How is Disney going to fuck up what came before?"-exercise.
After that's done, jump to a time period AFTER episode 9, beyond Rey, and do another trilogy. Create some MacGuffin Force thing in the Old Republic movies which turns up in the future films to tie them into some greater story.
Start with a blank canvas and move forward. There's a lot to work with which doesn't suck. The 7-9 stuff is easily jettisoned/ignored.