Consider an auto company network. behind firewalls and having
thousands and thousands of robots and other factory floor machines.
Most of these have IPv4 stacks that barely function and would never
function on IPv6. One company estimated that they needed 40 million
addresses for this purpose.
I guess I have a certain amount of skepticism that an auto company's
robotic control network needs to have public IP addresses.
In an ideal world, where it's like it was 20 years ago and we tell
everyone "register some space," yeah, it was a grand idea. Now, with
space running out, we need IPv6 for that, and in ten years, all those
little robots will begin to find themselves having their controller
boards replaced. There may not be a perfect path forward for them,
but it seems likely that they can actually deal with the problem in
suboptimal ways until they're actually capable of IPv6.
It is in no way thrilling, but it doesn't seem likely that IPv4-240+ is
going to be a grand solution for devices where the IP stacks are already
admittedly barely functional, or that public IP addresses are necessary,
in which case there's a certain amount of freedom to recycle as much of
the existing IP space as is needed.