This link describes the deployment of a new Sprint LTE mobile network as being done using Carrier Grade Nat with internal ip addresses which have been allocated the the US Department of Defense. Because the DoD network’s ip network is not connected to the public Internet, ip address conflicts will not occur.
This is of interest to us because it indicates clearly that the CGN model works and is actively being deployed by carriers even in advance of IPv4 runout. Whereas it has been a commonplace observation that the expanding universe of mobile devices would be a driver of IPv6 deployment, here as late as July 2012 we see a brand new mobile technology (LTE) being deployed with an IPv4 architecture.
This augurs for a longer horizon for IPv4 utilization and a longer duration for the IPv4 transfer market.