Disney certainly has the right to do whatever they please with both the MCU and Star Wars. The studio owns the movie/TV rights to both franchises, so it’s completely their prerogative to have them join forces within the same universe
Speaking with Yahoo, Marvel CCO Kevin Feige tackled the possibility of the Marvel Cinematic Universe crossing over with the Star Wars universe.
Feige revealed that he doesn’t “think there is any reason for it” while almost definitively shutting down the possibility of this happening in the future:
If you’d ask me if anything we’re talking about right now was in the realm of possibility 20 years ago, I would’ve said, ‘I don’t think so.’ But I really don’t think so. I don’t think there’s any reason for it.”
Looking at the history and future of both mega-series, it just seems unlikely that they would be able to find a common playground within which to play together