The problems of IPv6 deployment are ones of incentives, not design. Increasingly, the vast majority of services are accessed via the service cone of various CD

The problems of IPv6 deployment are ones of incentives, not design. Increasingly, the vast majority of services are accessed via the service cone of various CDNs and IAAS providers directly at edge servers local to them, and at some point it may be that the industry decides that it's not worth providing ordinary internet users the ability to talk to each other directly at all. At which point, we might just as well have stuck with IPv4. I don't particularly like that outcome, but it's possible.