In the consumer space this doesn't matter much. Most internet users at home could have their IPv4 address removed and only provided an IPv6 one.
Mobile internet is commonly served only by IPv6.
It's the hosting/server space where IPv4 matters and will probably be like this for the next 20 years. This will be harder than the python 2 -> 3 migration. We'll continue to come close to running out of IPv4 addresses but we won't ever ween off them completely in the server space.
> Most internet users at home could have their IPv4 address removed and only provided an IPv6 one.
> Mobile internet is commonly served only by IPv6.
These aren’t true. There are still some big consumer-facing sites that are IPv4 only — notably twitter.com and amazon.com. I can definitely still access both from my mobile device.
As far as I know, these middlemen are deployed by the respective ISPs and are not a core function of ipv6. I've had the 6to4 (or AFTR, I'm still not sure which) fail on my ISP and could only reach ipv6 enabled hosts, sometimes for hours.
Not strictly required for the ISP to run it, I think Hurricane Electric did/does run something like those for free. But in general, yes, it's on the clients to handle.
Mobile internet is commonly served only by IPv6.
It's the hosting/server space where IPv4 matters and will probably be like this for the next 20 years. This will be harder than the python 2 -> 3 migration. We'll continue to come close to running out of IPv4 addresses but we won't ever ween off them completely in the server space.