This produces 16.7 million new IPv4 addresses. Won't save the world but it is something. As for security issues, I think they could be shaken out with a transi

This produces 16.7 million new IPv4 addresses. Won't save the world but it is something. As for security issues, I think they could be shaken out with a transition period. In the first phase, ISPs would treat any attempt to use 127.{1 through 255}.x.x would be a hard error instead of a loopback connection, and none of the addresses would be assigned. So anyone using these addresses and expecting loopback would start seeing errors. In the second phase, some subset of the space would be made available for assignment and the majority of it would still be a hard error. Finally the whole thing could be opened up. At that point, we might find that some old devices won't connect to servers that have one of the new addresses assigned. For an IoT device, probably no problem, as long as the host it 'phones home' to is in the legacy IP space. Old Android devices that no longer get updates might be unable to connect to servers that use the freed up space.