But depending on how you frame it, that could be the point. TFA and TLJ definitely play into the idea of the cycle of good and evil, and even though you can’t destroy evil forever, that doesn’t mean it isn’t worth fighting against it.

So it actually might make more sense that there’s always a chance that Palpatine, who is basically the personification of evil in Star Wars, could always return.

I recall Dom having an idea of changing his last line to something like, “I have died before” and Rey saying, “I’ll be waiting.” (Or have them say nothing at all). Basically playing into that idea of people needing to be ever vigilant against the rise of evil.

BUT, if you did want to make it clear that he’s dead for good, I do think the Force ghosts playing some part in it, figuratively dragging him to hell, could help make his demise feel more absolute.