For me, no IPv6 = no business. I don't think it's acceptable to build a network on IPv4 only at this point, it speaks to being willing to cut corners and not do things the right way just because it's easier.
The people who attempt to fill these gaps are commonly rural telephone companies, electric cooperatives, tribal entities, or mom and pop shops where the owner grew up on a Ditch Witch and only knows as much IP networking as essential to light up the fiber and get the packets flowing upstream.
They are enormously resource constrained in ways you might not expect, too, eg operations can grind to a halt because everyone is out with a chainsaw after a storm, or because the Guy that Knew Stuff about their network died suddenly.
They are very, very unlikely to decide to run an IPv6 network just because. There's no upside that makes the juice worth the squeeze for them.
Saline is less than 10 miles from Ann Arbor.
> The people who attempt to fill these gaps are commonly rural telephone companies, electric cooperatives, tribal entities, or mom and pop shops...
That's fair, but at some point, you need to recognize you are competing with a major ISP. No one appreciates it when you come in, tear up the roads, and then pull out once the incumbent ISPs bump up their speeds ever so slightly. (Looking at you, Google.)
> They are very, very unlikely to decide to run an IPv6 network just because.
No one deploys IPv6 "just because," and yet more than half of the traffic to major sites is IPv6.
I live half an hour from a state capital and my only option is cable... the coaxial cable they laid bare on my flower bed decades ago. I dig it up about every other year when planting. It's not even in a conduit!
In an IPv4-only CGNAT setup, all the traffic has to flow through the CGNAT gateways, and that gear is stupidly expensive. Having IPv6 in the mix means that anything that supports IPv6 (such as most streaming services) won't hit the CGNAT gateway and can just be routed natively. This can really save money on CGNAT hardware.
For implementation, you can use NAT64/DNS64 for your CGNAT setup and implement 464XLAT on the CPE. This keeps your whole edge network IPv6-only so you don't have the complication of maintaining two parallel configurations on the edge.
There is also MAP-T, which is even lighter on infrastructure since it pushes all the state into the CPE and avoids the complication of stateful CGNAT. But unfortunately CPE support for it is pretty limited at the moment.
No state at the carrier; IP:6 native network.
If you buy a full IPv4 you get one for yourself but I expect still through the same tunneling machinery to keep the network IPv6-only.
I have spent most of my career under the thumb of fucking cable and I'd sooner slam a car door on my nuts than go back to paying so much money for such garbage service.