Well, it's also time to recognize and talk about the elephant in the room.

We know we can have an IPv4-only internet, we've been doing it for decades.

Our experiments thus far at an IPv6-only Internet have largely been (well, honestly, *compeletely*) unsuccessful.  In order to exist on the Internet today, you *must* have some IPv4 presence.  The reverse is not true; you can exist on the Internet with no IPv6 resources.

As a result, as you noted, the pressure to split IPv4 ever-smaller so that everyone gets a tiny piece of that essential pie is nearly infinitely greater than it is for IPv6. 

As a community, we have failed, because we never acknowledged and addressed the need for backward compatibility between IPv6 and IPv4, and instead counted on magic handwaving about tipping points and transition dates where suddenly there would be "enough" IPv6-connected resources that new networks wouldn't *need* IPv4 address space any more.

In doing so, we have sown the seeds of our own future pain and suffering.

By allowing IPv6 to be defined and established as an incompatible network protocol to IPv4, we ensured that IPv4's future was assured.

*Every* transition mechanism we have for networks today relies on having *some* amount of IPv4 address space for the translation gateway devices, which will continue to drive an ever-increasing demand for smaller and smaller chunks of IPv4 address space to be parceled out to every new network that wants to join the Internet.

The only alternative is that web-scale companies like Amazon and Google stand up swaths of IPv6-to-IPv4 translation gateway boxes, and provide 6-to-4 bidirectional translation services, with some clever marketing person figuring out how to make money reliably from the service.

At that point, new entrants could conceivably get on board the Internet with only IPv6 resources, with no need to scrabble for a chunk of ever-decreasing IPv4 space to perform the necessary gateway translation for their customers.

Unfortunately, because it's not just a mapping problem but an actual packet-level incompatibility, the companies providing the magical bidirectional translation service are going to be in the pathway for the entire bitstream, making it a bandwidth-intensive product to deploy.  :(

On the plus side, they'd have the best view into everyone's traffic one could ever hope for.  Forget just seeing DNS queries--you'd have visibility into *everything* the users were doing, no matter how tiny and mundane it might be.  Imagine the data mining potential!!

If I were younger, stupider, and much, much, MUCH richer, I might start a company to do just that...

Matt