What I think their last words would be:

Classic: "It'll just start over again..."

UnderSwap Sans: "The magnificent sans will not falter that easily!"

Dream: "Let me help you?"

Ink: "heh heh...so, guess that's it huh?"

Error: "I'll be back, bitch!"

Dust: "Ah well, I had a good run-"

Killer: "YOU KNOW WHAT?! SCREW YOU!"

Horror: "Welp, guess this is the end of the story"

Cross: "I'll protect you, no matter what!"

Nightmare: "I won't die, you can't do this to me!"

Ace(Chancetale): "My Universe is gone, suppose I disappear with it"

Exiled(my AU, Glasstale): "you can't be serious...right?"

Jester!(my AU again, Jestertale): "Hahaha! That was soooo much fun!"

(That's it for now, prob gonna make a SaMS version)