[matips]

I doubt we will see IPv6-only ISPs. Such provider will have to face complaints that some part of Internet is not working correctly. It can be written it in the offer, but for not technical people some services will be broken by ISP.

It is core of problem with IPv6 adoption - from ISP perspective it do not solve any problem because they still needs solution for connecting to IPv4. Opposite way it works - if you have IPv4 there are bridges to IPv6.

[ianburrell]

There are IPv6 first ISPs. There are ways to do IPv4 from IPv6. MAT does IPv4 CGNAT over IPv6 with stateless gateways. 464XLAT is used by mobile ISPs but requires software on each device. It wouldn’t work for ISP, but there is NAT64 which works well for companies and networks that can control software.

There is no way to go from IPv4 to IPv6.

[cess11]

It's not uncommon that 'security solutions' in commerce and the like just refuses traffic from IPv6. Sometimes I switch to a rather dirty IPv4 address to feel something when I bypass it that way.