Well, the big problem is that in order to make a model transform from a person into an animal, you'd not only have to make a new skin/texture for each step along the way, but you'd have to translate each vertex so that it fits with the new form. For most forms, the amount of vertices will differ between start and end forms, making the TF look unnatural very easily.
Anyway, full 3D is not going to happen for this game, and using it partially for certain scenes does not have my preference. Let's keep it at that for now.