Regardless of net opinions, I have had reservations accepting anything of the kind as IPv6 tunnels can be a security problem. None of the articles herein deal with the issue of irreplaceable IPv4 only legacy systems, such as building access control, fire, HVAC, and security panels.

From : http://www.networkworld.com/article/2985340/ipv6/arin-finally-runs-out-of-ipv4-addresses.html

The Internet Assigned Numbers Authority (IANA) delegates authority for Internet resources to the five RIRs that cover the world. The American Registry for Internet Numbers (ARIN) is the Regional Internet Registry (RIR) for Readmore..