Agreed. The main reason why it wouldn't work is that existing broadband deployments are not designed for P2P. Your neighborhood might have a gigabit of downstream bandwidth on fiber from the cable company but the upstream is limited to something like 100 megabits for the entire neighborhood. It sounds nice in theory to cut bandwidth costs, but somehow I don't think the cable companies are going to be too happy with you sharing their limited upstream with your traffic. They'd much rather deliver lots of streaming content downstream, which is what their network is designed for in the first place.