Source: http://blog.acostasite.com/2013/12/ipv6-no-te-vistas-que-no-vas-ahora-ipv4s.html
After a secret meeting almost a week in Switzerland, major hardware and software manufacturers worldwide took the drastic decision not to continue with the development and implementation of IPv6. Alternatively they unanimously decided to use the same IPv4 protocol and create a new concept of sub-IP (IPv4S).
Technical details are described as follows: "Let's use a bit that is reserved in the IPv4 header from source (RFC 791), the bit to be on the hosts will read the data fields indicating more IPv4 addresses, ie, is a subset of IPv4 ". According to the TNIV PhD Freq: "This is something that should be done long ago."