If every ISP decides to go with metered billing, the one business that can offer "unlimited" service will most likely reap the benefits, even if their current infrastructure cannot keep up with the demand at first.
That remains the problem for marketers of this idea. Like the "three strikes" idea, unless you get every carrier to engage in this en masse, then you're simply offering other carriers a way to differentiate themselves competitively.
Were Time Warner Cable a little smarter, they'd just impose high caps like Comcast, Charter, and Cox plan to do, then slowly ease them downward and impose overages in a few years very quietly while American consumers are busy guzzling corn syrup and watching Dancing With The Stars.
That's my suggestion, for what it's worth.