If Comcast is going to build the infrastructure, it needs to be able to make it from someone. If it is not to be from content providers, it has to come from content consumers. However, understandably content consumers aren't going to willingly pay more in advance of seeing a need, which they won't until they actually need it. The problem is that Comcast and other providers promised a speed that could be maintained with their current infrastructure if and only if there were only a few heavy users. The advent of streaming has upset that model.
The thing is, someone needs to pay for bandwidth. If not content providers, it will have to be content consumers.
You mean consumers might have to pay ISPs for internet connections?
And that if they start using more bandwidth, they'll have to pay more. I'm old enough to remember when ISPs charged everyone by the amount of data used and not just by the maximum speed possible. Given the changed dynamics of internet usage, they have the problem of having promised a maximum speed assuming that few users would be making constant use of that maximum. Getting people to pay more for the same maximum speed is not likely even if it does provide more total throughput.