About the Dune idea, I actually think Villenueve’s Dune trilogy (when it’s completed) would make a pretty neat alternate sequel trilogy. It would be set hundreds of years after the OT, with the opening crawl establishing the Bene Gesserit as being a sisterhood of Force users. The spice on Arrakis would be the same spice mentioned in Star Wars, and since they would still use hyperspace travel all connections between the spice and space navigation would be removed. Other than that, there’s not much you’d need to do, aside from giving it a somewhat more StarWars-y coat of paint.