Actually, I used to think Episodes 10-12 were inevitable, but now I don’t. Lucasfilm is definitely going to be putting more time into Disney+ shows from here on out, and while both spinoff movies were outperformed by all three ST movies, I don’t think that has anything to do with them being spinoffs. It just doesn’t look like they have a reason to make an Episode 10.
Just give it time, it is inevitable. Like there was no interest in the Matrix after the trilogy and 20 years later there will be a fourth one. I’m surprised if there is no Episode X in the next 50 years. At the same time I really don’t want it to happen.