Is there any wonder that moving to IPv6 is delayed? Assuming an average $25/address, that's $400m/class A. Some of the organizations that own a class A: Apple, Ford, Softbank, Daimler, Prudential, Comcast. Softbank needs the money and the others wouldn't sniff at $300m+. Not sure how long the 100m odd addresses would last though.
Comcast started rolling out IPv6 across their network a long time ago. They hit 100% support on their broadband network in 2014. They run a lot of the own stuff on IPv6, such as on-demand video on their set-top boxes. I think any home modem/router that they support that did not support IPv6 hit EOL long ago and was replaced. There may be some class A owners who are trying to hold back IPv6 so they can make money off…
Any internet service you want to be widely available will need to be dual-stack as long as we are alive.