I don't think there will be skins for other races - we do plan afterall on having completely different models for each race. Seeing as how we're very short on 3D modelers (and all of our current 3D artists have very immediate and important tasks) there is really no way to estimate when you will see an actual Diaboli, or a Lemur. My guess would be "long way off," but there can always be surprises.
It would also be a bit of a waste of time to make "temporary" skins - if they are going to be removed anyway, it's better that our 2D artists concentrate on content that is meant to be permanent.