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 the United States, Canada, the Caribbean, and North Atlantic islands. ARIN has been managing the assignment of IPv4 and IPv6 addresses and Autonomous System (AS) numbers for several decades. Each RIR has been managing their limited IPv4 address stores and going through theirvarious phases of exhaustion policies. ARIN has been in Phase 4 of their IPv4 depletion plan for more than a year now. ARIN will soon announce that they have completely extinguished their supply of IPv4 addresses.
At this point, the rules for how address resources are allocated will change. … To review the unmet resource policies, consult the Number Resource Policy Manual (NRPM) …. the policies in the NRPM will dictate that they are given out based on the Waiting List for Unmet Requests method. … The IETF created Internet Protocol version 6 and finalized the header format with RFC 2460 in 1998. …
Wikipedia.org can get you started learning the basics, you should visit the Internet Society Deploy360 Programme IPv6 page. You should also exploreARIN’s own Get6 site.
See also http://www.networkworld.com/article/2223398/cisco-subnet/ipv6-is-not-an-all-or-nothing-proposition.html .