I bet Steve would want to for a long time.
But it's an exclusive deal, so AT&T has the upper hand here, i think. If the rumours are true, AT&T has a 5-year-exclusive contract with Apple. That's still a lot time left. Ironically, this exclusiveness is some sort of lock in (from at&t's side) and here it's widely considered harmful :)
Meanwhile androids infiltrate all other major networks..