Time Warner announced, recently, that they intend to start testing usage-based-billing rather than flat fee internet access.
In a time when large bandwidth consumption has more and more legal uses (Xbox Live Marketplace, Xbox Originals, HD Video on demand through the Xbox 360 and other services like Netflix and iTunes, or even their constant music streaming service, RoadRunenr Radio), I cannot believe that there will not be an enormous backlash. I could understand this being a tactic to curb piracy nine or ten years ago, but now that the world is dependant on larger chunks of data, you cannot change the billing scheme that has been in place for over a decade.
Per-minute-internet access is still used in some countries, and I, personally, know a few people who still have to dial long distance numbers just to check their email. Nevertheless, I am ten thousand percent opposed to this idea, and hope it does not come back!