Majority of Wind based attacks aren't flying type. I'll have to get a full count when I'm on a computor, but right off the top of my head, Silver Wind (bug), Icy Wind (ice), Ominous Wind (ghost), Gust (flying), Hurricane (flying), Whirlwind (normal), and Razor Wind (normal). These I remember right off as definate wind based attacks. Going to look up the others if there are others, but my point wind =/= flying in every aspect.
So Sylveon being wind doesn't mean its guaranteed Flying. They can sneak in another type pretty easily.
My only question is: If the moves in the trailer were Focus Blast, Swift, Trump Card, and Future Sight, can Eevee and its evolutions learn all four? The evolutions and Eevee are usually very limited in their move pools due to Eevee's ability to have a large number of evolutions. I can't see it learning Focus Blast and Future sight if its Flying.