Well, I am slightly surprised at the views of some people, one of which was a comment on my "Kick starting IPv6" post. Some people want to stick with IPv4!
Perhaps this is just resistance to change or being devil's advocate or trolling. I am not sure.
The reasons for sticking with IPv4 also made no sense - they appeared to be around wanting some basic fire-walling, which applies as much to IPv6 as to IPv4, rather than actually saying there was any problem with IPv6 as such.
Basically, IPv4 runs out. Running out comes in several stages, starting with IANA running out in a few months, the RIRs, then in various degrees ISPs running out.
So there will be no end of bodges and multiple layers of NAT and web sites on odd ports. Things will get less reliable on IPv4. Eventually you will get to the stage that web sites and other "services" start to work better on IPv6 or have less quirks or restrictions, and eventually some will simply "only be available on IPv6". Mapping systems to allow IPv4 users access IPv6 will be a similar level of bodge with limitations.
So sticking with IPv4 is not ultimately an option. Its like sticking with dial-up or sticking with analogue TV. Eventually you have to change, or put up with failing and inferior services.