the one scene that matters in the whole book

I wouldn't make that assumption. There are several chapters left and a bunch of things left unresolved, some of which seem like they could be important. Is he going to make further progress on defeating Death? Will we discover why there's a prophecy that he'll tear apart the stars, empty the skies, and end the world?

Maybe not; there might be nothing left now but wrap-up. But I don't think it's a foregone conclusion.