I totally agree that containers in general, and Docker in particular, could play a big role in moving the status quo towards IPV6 and a more sane approach to service-oriented networking. I would love to turn on IPV6 by default on every Docker runtime everywhere - the question is, how do we deal with 1) existing host systems, 2) existing networks and 3) existing applications which may not be IPv6-ready? We are already upgrading the guts of Docker for more powerful networking and clustering in general, so if you give me a solid answer we can get this out the door pretty quickly :)