I originally thought that as well, but I recently went back in the Dark Castle and looked at the map drawing. The 3 new biomes are drawn in the same scale as the Valley biomes, and there's also that arrow implying the 3 biomes are to the left of Sunlit Plateau/Forgotten Lands.
The way they've worded it, I honestly can't imagine how they'd give us more space without a new biome as one of the features. Whatever ideas they've got in mind, I hope the overall Valley layout gets a rework to make it feel more complete like Eternity Isle. I'm also excited about the new Tiana restaurant, like when we got Daisy's Shop, I wonder if we'll get daily challenges from Tiana as well?
Multiple saves would be neat because starting at the beginning with knowing how to play could be fun. But, I honestly would prefer more biomes. I especially want a candy biome, even though we did get candy trees and paths, and a “city” biome. I want a place to put all the buildings that look more modern. Also a “parks” biome would be nice because there are so many rides now.