Of course we will, but it wont be called Facetime, obviously.
It will change everything in terms of the way carriers price contracts and handsets, so they will need to be on board.
I think Blackberry has been given the chance to do it because they are a relatively small market now, especially these newer handsets, so they can test the water without making much of an impact.
Similar to when the iTunes music store first went online it was Mac only, again a relatively small number of users, so if it worked out to be detrimental to the music industry the impact wouldn't be severe.
Its definatly coming though, the carriers are probably doing the maths and figuring out how they can squeeze more money out us by doing it.