haha, then what?

mad again. crowley's whole point is that humanity doesn't deserve to suffer for the crimes committed by heaven and hell, so his solution is to create a new universe without angels or demons. sacrificing themselves for humanity, sure, I get it. but what about all the humans who were wiped out with the book of life? god gave them the option of returning all those humans, and instead his solution is to start all over a la the great flood, something crowley was staunchly opposed to. so not only is there no happy ending for crowley and aziraphale, but there's no happy ending for recently corporeal jesus, or mrs sandwich, mr arnold, nina and maggie, adam and the them, newt and anathema. it's job's kids all over again. they didn't want the new children the angels offered them, job and sitis wanted their children back. it's the same choice they gave adam. he wanted things to go back to normal with heaven and hell behaving themselves so he could play with his friends. how could crowley and aziraphale be happy sacrificing their existence knowing it condemns all of the humanity they know and love?

The destruction of the entire universe and every soul in it is a truly depressing ending. Just because God replaced it with another universe that looked similar doesn't change anything - this is Job and his children all over again. Job doesn't want new children, and neither do I.