> What makes you think ISPs' projections for traffic using your protocol would look any different from their projections for IPv6 traffic?
Once again: all value of the network is on its edges (i.e. the hosts have the content and the clients). So, if DJB's plan was followed, all hosts would _already_ be configured for IPv6 _now_ (because he wrote that 8 years ago) and they could _talk_ IPv6 _now_. This would happen during routine OS upgrades.
With IPv4 address crunch coming, ISPs would have a clear _solution_ already in place, so they could easily put people on IPv6 addresses, because they would _just_ _work_ with the rest of the Internet _now_ (there would be no interoperability questions). Ergo, investment in IPv6 before the crunch would make sense, because everyone could talk IPv6 immediately, without involving any kind of reconfiguration, workarounds, 4to6, toredo (am I spelling this right?) and whatever else was proposed along the way.
> I'm sure they would have figured they could get along just fine without paying extra for hardware capable of carrying your hybrid protocol, just as they have with IPv6.
Sure. However, with all the hosts out there ready, configured and capable now, why would they avoid IPv6? Why would they be investing in multi layer NAT when IPv6 would already be deployed around them? Could they really risk being taken out by the ones that didn't do that?
For instance, my ISP is fully IPv6 ready on their core network, but they barely have any clients on it (just a trial). Had DJB's suggestion been followed, I'd be pinging ipv6.google.com today, without touching anything and my ISP would be in the position to eat other people's lunch if they didn't go for IPv6. After all, addresses will become tight. Putting people on real IPv6 addresses is the cheapest thing to do. And it would just work.
You know, it's like AMD64. At first, people had these things and nothing 64-bit to run. Chip makers stuck to it and little by little, people found ways of using this. IP should have been done the same way.