Heck, if I were Level3, I might even drop the level of traffic in my own network bound for Comcast and have a note on the site that Comcast users can expect poor performance. Something like "Comcast is too poor to upgrade their network and has attempted to extort payment from us under threat of disconnection from their internet users. Though we have refused to pay the "eyeball ransom", we have decided to help Comcast out anyway by bandwidth limiting traffic to their poor wittle network. As a result, Comcast users might experience reduced performance."
Note that was tongue in cheek. I actually support the notion of making it more expensive to deploy more bandwidth intensive applications as it *does* place an unfair burden on the delivery network. The problem I have in this case is the conflict of interest when the delivery network is also a content provider and discriminates against content competitors.