The original RFC came out in 1995, the modern RFC used today in 1998 - almost 25 years ago. When I was in college in 2012 (going through the Cisco NetAcad) they were preaching that our IPv6 future was "just around the corner". I am going on 10 years in network and security now, and I still don't see it. At least in the US, IPv4 is, and will remain, the dominant force.

There are many reasons for this, but one of the biggest is - from a practical standpoint, the only thing wrong with it is the lack of addresses. Even the perceived shortage is hardly felt though - what is the going rate of an Elastic IP not associated with an EC2 instance these days, $0.005 per hour?