Re: "We have now run out of IPv4 addresses"
Honest question - why can't we do this?
Besides that nobody has programmed it, there is little practical reason. If somebody did program it up, I honestly think adoption would happen at practically breakneck speed compared to IPv6 because everybody would know and be happy with what it's doing conceptually without requiring comprehensive retraining.
In the real world nobody practically nobody actually gets this training on IPv6 and so practically nobody is willing to have anything to do with IPv6 because it has no benefit for the business, while presenting the exciting possibility of losing your job if the IPv6 design goal of "make all of my endpoints available to hackers" hasn't been adequately circumvented.