“if you kill a whitewalker, all his wights die as well. We have never seen more than a dozen or so whitewalkers at once so far, so that seems more manageable.”
If you can get to them. So far as we know, other than wild cards like the Horn of Winter and whatnot, that have been almost forgotten in the story, all the dragon glass in the world may not be enough... Lets face it you get killed, then you raise and are fighting for the enemy...
And the most powerful single beasts on the field, are the dragons, of which the Night King has one, and killed it easily, in flight, with a single spear throw.
Obviously SOME will survive the battle, no matter how the battle turns out... but I would expect a twist of some sort if you expect them to win.. My guess is it will be a twist of some sort that simply allows some of them to survive.... let alone win... We shall see.
The story seems weak if the Humans win, their first confrontation with the Night King.. especially when grossly outnumbered... The rest of the 7 realms likely won’t even believe it even happened, if they are stopped at Winterfell, it would just be legend, as the majority of the continent will have never seen anything.
I could be wrong, but I would expect the final battle for survival of humanity, to be later... not here.
The all die! The final scene is thousands of years in the future and there’s this whitewalker telling a little whitewalker about this icky pink warm things called humans!