AT&T should be welcoming current users to buy a new iPhone, regardless of when they purchased their last one. All it does is binds them to another two year contract. They are not losing any money by forcing me to renew for another two years. They are actually ensuring that I will remain an AT&T customer longer -- something they should WANT to do.
Of course, if Apple does not renew THEIR contract with AT&T, maybe I'll be happy I waited to buy a new iPhone. AT&T has done nothing but screw iPhone users with unnecessary costs. I'm sorry, but it does not cost $10 MORE a month to provide me 3G connectivity. And it CERTAINLY does not cost $40 a month more to allow to to tether my iPhone to my laptop. AT&T can drop dead.