Hey, what you describe what clearly the case with old peer-to-peer systems, but things changed a lot.
With webRTC and ICE/STUN, the p2p connection takes less than 5s on average and goes through NATs in 95% of the cases.
As for the bandwidht issues, it is not a problem as the solution is hybrid and doen't need every peer to be a full seeder.
If you don't beleive me you can always try by yourself, with a Chrome/Firefox/Opera browser : http://demo.streamroot.io
one connection takes 5s, but using a stun server means you don't understand peer locality. This means you as the service owner has to map the network to find correct peer placement.
How do you asses the bandwidth available now, and in the future? is the bandwidth between two peers inside and ISP greater than two peers from different ISPs. How do you manage peer re-routing when one disappears. What happens if more than one peer disappears?
webrtc is designed for 1 to 1 mapping, and not 1 to many paid for content delivery. Sure you can do it, but your users arn't going to be happy you chose to engineer your way out of a bad idea. (You don't want buffering during an expensive movie/tv/sports game)
If you don't beleive me you can always try by yourself, with a Chrome/Firefox/Opera browser : http://demo.streamroot.io