I'm 100% positive this thing was inspired by Frozen. It came out right after X and Y, and Frozen fever hit Japan really really hard. Essentially if you were a Pokemon designer for Gen 7 trying to create new Ice Types it would be impossible to NOT think of Frozen for inspiration, it was so dominant and got the aesthetic of snow and ice so perfectly.

Also I can't quantify this but A.Ninetales just LOOKS like Elsa, I know I'm not remotely alone in thinking so. Could also partially explain why it is Fairy Type, since Fairy might as well be called the Disney Magic Princess Type.