I would be honestly surprised if Disney outright de-canonized the Sequels. I imagine the best you could hope for is soft reboots where they just don't reference the events of the ST. Maybe if they sold the franchise to Elon I could see him doing this kind of audit and trolling but otherwise's seems a fool's hope.
As for splitting canon, that isn't a bad idea. Indeed I argued the EU always should have been it's own distinct canon from the get go. The primary issue as I see it would be one of practicality. I fear one canon would become the defacto "primary" universe and the other regulated to more a footnote not wholly dissimilar to the current arrangement of Disney and Legend continuities.
Eh, Disney started by decanonising the whole EU. If another decanonisation is sold as a deliberate course-correct by a whole new management, it could easily work. Countless franchises have been rebooted multiple times, after all. And at times, unpopular iterations have been very openly given the boot, precisely to win back fans.
That said, I don't see that as a likely outcome. And frankly, I think an entirely new owner would be a much better solution. In that case, "disney canon" getting pushed aside would hardly be surprising. A new owner wouldn't want that baggage.
The way I'd see things going, quite frankly, would be that the original EU canon and the Disney canon would
both become pretty much "secondary", and a new owner would start over with a
third canon of their own. And that would become the primary one.
Were it me, however, I'd only keep the (relatively few) good bits of the Disney canon, to disassociate myself from
that mess while still keeping the stuff that people actually liked. Meanwhile, the original EU had mostly run its course when Disney bought SW. But here's the thing: I'd invite authors to both add new stuff to the truncated Disney canon (as long as it's different from the decanonised garbage),
and to add more entries to the original EU. For the latter in particular, there were some works that just got unceremoniously cancelled or were left unfinished near the end. I'd invite the people involved to finish that stuff, thus hopefully making the EU fans quite happy.
As for the "primary" canon: like I said, I'd go for a 2D-animated universe, closely based on the old EU, in many cases adapted directly without any alteration, but with some of the really bad parts cut out (and possibly replaced with better things). After all, since the EU has been 'dead' for over a decade, it's now become pretty clear which elements just never quite landed, and which remain popular to this day. Putting the stuff people love on the screen would bring joy to most fans; both old and new alike.
Fans want to see the Thrawn trilogy on the screen, but few people desire to see an adaptation of
The Crystal Star or
The Glove of Darth Vader. Meanwhile, most of the Callista trilogy could be cut, while parts of it could be re-imagined into a good story of how Pellaeon comes to be in charge of the Imperials. And that's just some post-RotJ stuff. Have you considered a multi-season epic about the Mandalorian Wars? A historical drama about the Pius Dea crusades? Not to mention the ready-made source material in the
Tales of the Jedi comics...
You can have your cake and eat it too when it comes to divisive stuff like the Revan novel: the book stays part of the original EU and thus canonical there, but youy do things differently in the animated universe.
The possibilities are endless.