Its mearly a thought. My mind keeps changing as different theory arise. I think (this is pretty much only me, but would explain the japanese name of Ninfia quite well) that it will be a new type. And whats my type suggestion than probably no one has though of? Fairy. Fairy type is my assumption. Think about all the fairy-like Pokemon.....they are almost all pink. And what is Sylveon? Pink. Its just a thought. I'm nearly 100% sure that it will be a new type though.
....also, why is everyone speculation flying type? It makes no sense. There is now good eveidence to suggest this theory being a legitimate answer.