Almost all mobile phone providers in the US are switching over. They never really offered full IPv4 in the first place, with their networks fully NATed. But they're introducing real, routable, IPv6.
From personal experience, on T-Mobile if your device supports it, you can even use IPv6 only (that is, your device only gets an IPv6 address, not even a NAT'd IPv4.) If you try to access an IPv4 only site, T-Mobile's DNS provides a virtual IPv6 address that can be used to route outgoing TCP connections to that address via a proxy.
Now, some people would be unhappy with that situation if, say, Comcast were to do the same thing. But I must admit, I suspect 99% of the population would never notice, and over time, the few that do would find, say, their employers scrambling to have IPv6 gateways etc so they can use normal VPNs (the gateways to office networks, not the proxies for bypassing Netflix nation blocks I mean), and other applications that require full two way communication.
IPv6 is very nice. It really is a shame there's so much inertia.