writes "Several major Internet Service Providers in the United Kingdom, including BSkyB, Virgin Media, TalkTalk, AAISP and Fluidata, have warned that the adoption of Carrier Grade NAT (IPv4 address sharing) is likely to become increasingly common in the future. But the technology, which many view as a delaying tactic until IPv6 becomes more common place, is not without its problems and could cause a number of popular services to fail (e.g. XBox Live, PlayStation Network, FTP hosting etc.). The prospect of a new style of two tier internet could be just around the corner."
A few of the ISPs gave the usual marketing department answers, but three of them noted that they've been offering IPv6 for ages and CGNAT is only inevitable for folks that didn't prepare for what they knew was coming. Which, unfortunately, appears to be most of the major UK ISPs.