It is likely to happen, if you look the specific description of ToV on the general namco bandai site you'll notice that in the news section they always refer to it as "Tales of Vesperia for the Xbox360" http://www.namcobandaigames.com/news/press/press/307
You will never see the word "exclusive" or "exclusivity" on games which are only time exclusive or with a strong potential to be ported.
But when you look at an exclusive title, like for instance Cudcept Saga or Naruto Ninja Storm they will refer to it as "exclusively for Xbox 360" http://www.namcobandaigames.com/news/press/press/272, "exclusively for the PLAYSTATION®3 computer entertainment system." http://www.namcobandaigames.com/news/press/press/282