I really, really hope that Sylveon is a Bug, or Flying, or Normal, or whatever, just not Fairy. I really dislike designs that are extensively girly and only exist to be cute(see- Lilligant, Gardevoir, Bellossom, and Audino[note I don't hate any Pokemon that's kind of girlish, like Gothitelle or Wigglytuff, just ones that are clear-cut made for little girls whose minds are filled with happy rainbows and unicorns]). I prefer designs that are absurd and creepy like Dusclops and Shedinja(also why I love Porygon-Z). A Fairy type just seems like something too weird, even for GameFreak(yes, I KNOW you can somewhat present the same argument for Dragons, but I'm not that big a fan of Dragons either). I'd prefer something like Sound, Cyber, or even Light, if I was forced to make a new type, because I don't like new types at all and would prefer just to stay as is.
Fairies don't have to be girly, there are a ton of mythologies and folklore that portray them much more differently then people give them credit for (for instance, goblins can be considered fairies).