I'm curious how much of this is due to mobile devices. For as long as I can remember, I have had IPv6 addresses on both Verizon and T-Mobile (though only T-mobile allows IPv6 traffic as of last year: http://www.extremetech.com/mobile/145765-ipv6-makes-mobile-n...)
I think mobile networks do play a good bit of a role here. My iPhone 5s is on Verizon's LTE network and connects over IPv6 to sites. If you look at the latest World IPv6 Launch measurements from Jan 16, you can see that 40% of the traffic that was measured coming from Verizon Wireless' network was coming over IPv6 - http://www.worldipv6launch.org/measurements/
(Those measurements show the % of IPv6 traffic from various operator networks seen by Akamai, Facebook, Google and Yahoo.)
