Except what reason do we have to believe that Palpatine is gone for good this time? At least Dark Empire, for all its issues, bothered to explain how the heroes were able to prevent Palpatine’s return in future stories, ensuring that he could never come back to life. After TRoS, though, what is there to stop Palpatine from just possessing a new body somewhere else? Is he going to be like Sigma from Mega Man X and just keep coming back over and over again until it becomes comical?
Worth noting that the canon novelization for TRoS does say there’s really no way of being sure Palpatine isn’t just gonna come back again.