Um…I think being thrown down that massive hole/shaft into the bowels of the Death Star which itself was then blown to smithereens is a pretty conclusive “He’s dead” to me.

I personally think that it being Vader who kills the Emperor rather than Luke is brilliant. It not only allows for Vader’s redemption but it also perfectly fits with the Sith “Rule of Two” where the apprentice kills the master. So Vader both embodies the Sith tradition in that moment but the way it happens is undeniably an act of good and sacrifice to save his son. Luke throwing away his lightsaber in defiance of Palpatine was also what Vader needed to see since he himself didn’t have the strength or conviction to do the same back in ROTS.

I think you might find this video interesting: https://www.youtube.com/watch?v=-2BNdF_NCVQ

The ST bringing back Palpatine was a huge mistake. I love Ian McDiarmid but Palpatine should have stayed dead. Some say that making Snoke Darth Plagueis was a bit too obvious but I disagree. It would have beautifully tied the ST together with the PT and OT and most fans probably wouldn’t even know or remember a single thing about Darth Plagueis from ROTS. For years there was no doubt in my mind that Palpatine died in ROTJ. I personally didn’t need it to be confirmed any more than what was already on screen.