Zero mention of firewall problems?
There are a few more gotchas, which is why I applaud the comment about making sure you can spot IPv6 devices on your network.
The challenge IPv6 brings is that it has more features that your firewall either doesn't know about, or that will force you into a decision to support it or not.
The extensible headers in IPv6, for instance, were identified as a risk some good 10 years ago because you can easily build a covert communications channel with those. The problem with all those features is that, the Internet being the Internet, someone will come up with a way to use them that may be useful and then you'll be facing the problem of traffic inspection et al.
One of the nice features of NAT was that it made a device less addressable if it didn't originate the connection because there was no return map for the traffic (the router would not know which internal IP address to forward the traffic to). IPv6 can allow direct interaction with devices on your LAN if there's no similar approach in place, and that is a recipe for all sorts of problems.
Yes, we have to IPv6. No, it won't be easy. We will now have to learn what countries of Japan have already gone through a while back. Ironic, because the US limited the IPv4 pool Japan could have, they're now something like a decade ahead in IPv6 deployment and use..
Biting the hand that feeds IT
