Comcast hasn't taken the next step YET - but it is coming as has been seen with other ISPs. And that is "bill by bytes transferred" billing tiers and overage fees.
would "bill by kilobytes sent" billing be so bad?
(it simply means that the sender of the data pays but not the receiver. sound familiar? this is how the postal and telegram works. Bonus! Advertisers might then consider how big their fancy flash ads are)