No reason to think they are done, given how much time is left and that about a third of the core races still haven't really gotten anything new apart from hairstyles, skin/eye colors, and maybe splitting up previously linked geosets for facial hair or features. I'm assuming that they're trying to get all the races to the same level of customization as night elves, orcs, and tauren, or at least dwarves and trolls.
And they've already said this is an ongoing project that will continue beyond expansion launch.