I think it makes sense. I hope this doesn't complete them though. Sylveon is pretty girly. I'd feel wired having that in my team lol. We need a ground type to complete the X/Y theme and have it be the "guy" version of the Sylph counterpart.
Hopefully the X/Y coordinate theory exists so Ninfia will have a ground-type counterpart. Maybe each eeveelution can be exclusive to their respective versions. Although that's just fan speculation.
I hope it happens too. Maybe it has to be exposed to a certain gene/genome to evolve on the game. --- **** you SE for trolling us with that TWEWY port. I hate you.