Acting under the assumption that the PS4 is about ~5 times as powerful as the Wii U, then the difference could be 720/30fps for the Wii U version and 1080p/60fps for the NX if the NX's power is comparable to the PS4.
If the NX is substantially (but hopefully not severely) less powerful than the PS4, as is currently expected, then I would imagine that the NX version is 1080p/30fps with significantly improved textures.
With Windwaker being 30fps on the Wii U, I think this may potentially set a precedent that Zelda will be a 30fps game for the foreseeable future.










