One of the foremost obstacles to wide adoption is that IPv4 still works great and it's ubiquitous. There is no advantage or up-side to deprecating or abandoning IPv4 support at all. The only result of disabling IPv4 is a denial of service to a certain sector of customers or clients.

The only way this will change is by increasing pressure on the resource of IPv4 networks. It was a few years ago that AWS broke the news to me that I'd be paying for IPv4 addresses but IPv6 would remain free. If enough services are forced, financially, to abandon an IPv4 presence, then their clients would be likewise forced to adopt IPv6 in order to retain connectivity.

But with the ubiquity of CGNAT and other technologies, it seems unrealistic that IPv4 will become so rare that it becomes prohibitively expensive, or must be widely abandoned. So that availability of the legacy protocol will inhibit widespread adoption and transitions to IPv6.

Yeah the reality is that the Internet is centralized now. There is no reason for two computers on the internet to connect to each other anymore, as long as you can reach Google/Microsoft/Amazon/CloudFlare, that's all anyone needs.

Just log onto AOL and type in keyword "WALMART" and save! It's friendly and safe.

In theory you can save quite a bit on AWS costs by having instances that can only use v6.

But in reality at the moment there will probably always be at least one thing that only works with v4 a lot of the time.

Incentives are misaligned as well - it saves you money as the EC2 instance user, but the owner of the website you're trying to access has to support v4 anyway so they don't have a big incentive to change anything

Maybe it's time to tax IPv4 usages or holders.