Obviously, Jon should have been one to do it. Its the obvious choice because he's the most invested, been warning everyone about them, had basically the entire show invested in it. He should have been the choice because in story-telling, that's how you get payoff.
There are parallels to the scene in No Country for Old Men, where Josh Brolin is gunned down by Mexicans in a gun battle we never see. But that's not really blue-balling you. The entire movie's theme was random chance and the strangeness of it. So it was acceptable to the audience. Was it unexpected? Sure. Did it subvert your expectations? No, because the themes and dialogue and cinematography was built around this bleak darkness of randomness, chance and unstoppable forces.
The problem is that there's no such thing in Game of Thrones, Jon should confront the Night King. He should be the one to vanquish him, because that's basically his story. If you want Arya to do something, have her distract his lieutenants and start murking them, while Jon dukes it out one vs. one. Things get more and more desperate as Arya struggles not to get hit and you have Jon kill the Night King.
The problem with Game of Thrones has always been it that it has gone for shock value over any sort of real story-telling or substance. Narratives don't get any payoff not for thematic reasons, but because its shocking. Subverting expectations in story-telling can be done well. You can have this evil piece of shit fighting the good guys, but it turns out he was right all along. The thing is, thematically, tonally, you need to set this up. They never, ever do that.
Cersei's death or non-death would be hilarious. The amount of salt that would flow from her being the one to take the Iron Throne would make me laugh so fucking hard. My thing is, after about the fifth season, I've got literally no investment in any character. They fucked that season up so bad, there is no way I could ever see this as a dramatic show ever again. Its a garbage fire that I watch on Sunday, written, produced and directed by terrible fucking hacks.