I don't know the availability of IPv6 web sites at present. Certainly none of the hosting firms I've used over the years seems to have made mention of supporting it (so far) and while I've not been actively seeking IPv6 hosting, I've also not been thinking too hard about the old kit I have which is pretty much exclusively IPv4, and think a Carrier NAT solution could be a method to test the 'Carrier level' hardware and later offer IPv6 on the 'internet' side rather than customer side, IYSWIM. While that's not the intent, it serves to allow expansion of customer numbers for a while longer.
It would work as a fairly good intermediate step, so long as problems from the NAT feature don't mess too many people about. Can see it being unpopular with peer-to-peer users, perhaps, but many other services should be tied to username/password controls over traffic limits, connection limits, etc, rather than IP alone.
For many 'home users' it will be fine, and if only torrent users are affected, it's going to perhaps need some creative explanations about what the problem is, when a teenager finds they're unable to get the music / film / porn their friends are downloading...
I'm planning on fibre and lower speed BB with different ISPs over the next few years so will (hopefully) be able to cope with whatever goes on. My older XP systems will eventually die anyway, and the IPv6-ready kit will just need switching to the more 'go-ahead' ISP when IPv6 is rolled out by them.
If you run a business, have a second ISP and backup web hosting...
1996? Enterprise (IoM 0345) + Clara.net
1998? Clara.net + Freeserve
2000 Freeserve 500kbps (+ Clara dial-up + Clara USENET/Mail)
2002 ? Eclipse 500 kbps + FS
2003 ? UKFSN 1000 kbps + Eclipse
2005 ? PlusNet 8 Mbps+ Eclipse
moved home - used office BB
2008 Three dongle at home
2010 PlusNet 2 Mbps + Three dongle
2012 PN 10 Mbps + Three (ZTE 802.11 router) + Three mobile (802.11 hotspot)
2013 PN 30? Mbps + VM 30+? Mbps + Three mobile