I'm really curious about the Western Reaches books versus the Cursed Scrolls that will apparently contain overlapping information. I have no doubt that Kelsey can kill it with creating a setting, but the areas we know about from the Cursed Scrolls don't, at the moment, feel like they fit into a cohesive whole. I assume the Western Reaches books will include connective tissue.
Most of her settings so far have been lightly sketched and supplemented by the random tables in the core books. It'll be interesting to see if she takes the same approach with the Reaches (similar to how Yoon-Suin works) or if she goes for a more detailed treatment.