[jsz0]

IPv6 has been such a wild ride. About 7 years ago there was a big IPv4 depletion scare when ARIN made it harder to obtain IPv4. I did a bunch of dual stack deployments for customers around this time. In subsequent years quite a few of them ended up paying us to come back in and un-deploy IPv6 as their network engineers or often 'the IT guy' neglected to maintain firewall rules and access-lists leading to major security issues. I can't really think of any other vital technology like this that has rotted on the vine and had so many false starts.