AT&T to limit iPhone data plans?

It seems that AT&T is regretting the unlimited data plans that are provided to all iPhone customers.  Due to a small percentage (three percent) of extremely high bandwidth usage customers, the available 3g bandwidth for the entire network is being reduced by 40%.  They say this is due to high bandwidth video streaming applications such as CNN's mobile app.  As a result of this imbalance, AT&T wants to impose a limit on smartphone monthly bandwidth, such as the one that exists for their connection cards.  Will it fly?  At this point, who knows. Will there be fallout if it does?  Let me say this:  When AT&T loses their exclusive hold on the iPhone, I for one don't plan on sticking around.