These new books would start out just like current novels. At first, you wouldn't even know that anything was different. You would be drawn into a carefully developed world, with realistic characters playing out their lives' drama against a sweeping, deep history. This would pull you along, page after page, until about three-quarters of the way through what a "normal" novel would be.
Then the real twist would come. Instead of all the bother of reading through an ending, with boring conflict resolution and denouement, there would be a short synopsis of how everything wraps up. In a paragraph or two, the author would give you a quick sketch of who lives, who dies, and how the protagonist succeeds (or fails, depending on the flavor of the story).
It's a perfect solution!
And there was much rejoicing.