Of course. But it can't be turtles all the way down - at some level, the overlay traffic will be a TCP segment or UDP packet, sent from one node running overlay

Of course. But it can't be turtles all the way down - at some level, the overlay traffic will be a TCP segment or UDP packet, sent from one node running overlay network to another node running overlay network. If both nodes in the overlay network are behind the two "cone" NAPTs like this: A --- |> --- <| --- B then getting from "A" to "B" is not easy. And the "cones" may be of varying degree of aggressiveness when it comes to filtering [1]. You can not guarantee that you can always establish connectivity between the two, even in a presence of the third party - with the addresses being more and more precious, the SPs will move from full-cone to more restricted NAPTs. Besides these hurdles, moving large volumes of traffic atop overlays is not very optimal - I heard anecdotes that when Tor is abused in this manner, it is quite slow. Skype (and I guess probably Tor as well) uses supernodes that are not behind the NAPT to establish the communication. As there is less and less places for it. So, the quality of communication over overlay degrades more and more. Meanwhile, the bigger players will just place the caches close to eyeballs or directly peer with the eyeball providers. [2] So, I think Lee's scenario is quite plausible. Pretty much the only things keeping holding IPv4 in my home network are the client device bugs [3] and Skype. The web works quite well on DNS64. I think the economics will take care of things. There are users on IPv6. A few clever interns last year made a website [4] that aggregates various IPv6-related stats. Take a look at the situation with users e.g. in Germany, Belgium, Switzerland. Yes, it is still not a whole lot but it is growing - and these three give the impression of how it might happen - sometimes steady, sometimes the switch will just turn on. I am very curious to hear some VC chime in on this matter - what do they think about the prospects of business growth in the situation of the constrained address space and uneven competition. It is not the case today because ARIN still has numbers. Give it a couple of years. [1] https://en.wikipedia.org/wiki/Network_address_translation https://en.wikipedia.org/wiki/Network_address_translation [2] http://blogs.broughturner.com/2009/04/googles-peering-and-caching-strategy.html http://blogs.broughturner.com/2009/04/googles-peering-and-ca... [3] https://ripe66.ripe.net/archives/video/1196&#x2F https://ripe66.ripe.net/archives/video/1196/ [4] http://6lab.cisco.com&#x2F http://6lab.cisco.com/