But that bandwidth usage will localize more and more and may start going over really non-traditional mediums that weren't fully integrated into the "network mesh" before. If there are 200 people in a shopping mall, with 50 of them with some LocalCDNEdge app enabled and acting as beacons -- the request may never leave the shopping mall and return data that is fresh-enough (depending on the use case of course). Yeah there's now kind of a P2P gossip storm going inside the shopping mall, but I don't think that can't be solved with some more intelligent algorithms and at the worst case, just another wifi-router-as-pop.
I mean unless I'm thinking about this wrong -- what I'm envisioning is the CDN pop solution, just with WAY more pops. Yeah you have to coordinate the pops, but delivering the same payload to two people who are right next to each other (same apartment building let's say) from the far away CDN pop is less efficient than delivering it to one of the people, and P2P for the last mile so to speak.
Also, I think I can lean on innovation emerging in the network space for how to manage this kind of thing -- "Edge" is a buzzword now but I think there's a more innovation to be had.