Re: Bridging IPv4 to IPv6
Facebook, Google, and countless others already offer native IPv6 to their services and have done for some time. I use them daily on AAISP without issue. For that matter, dual stack can and does work seamlessly if setup correctly.
Thinking in hex is not that difficult - if someone is bright enough to do subnet/netmask calculations with IPv4 then IPv6 will come fairly easily to them. Other than concepts like link-local addresses, the different packet structure, and no NAT, they are administered in virtually the same way from an end-user premises perspective - firewalling being part of any solution. My network has been native dual-stack for a good six months now, and had tunnelled v6 before that - the big boys like BT need to stop dragging their heels.
The biggest misconception I see is that publicly routable addresses are somehow wide open without NAT. The packets still have to pass through your router, and are therefore still subject to firewall rules. IPv6 is coming sooner or later, whether they like it or not. Might as well be ready :-)