Why is it that were not using it more?
Of course, there are use cases for IPv6 and where it is the best solution it is being used. But where IPv4 gets the job done it is very hard to justify replacing equipment just for the sake of being IPv6 compliant.
The use of NAT64 is helping many organisations to delay migrating to IPv6. From a purists point of view it is probably not an ideal solution. But it seems to keep the pragmatists happy.
> The use of NAT64 is helping many organisations to delay migrating to IPv6.
That's...not how NAT64 works. NAT64 is fairly dependent upon deploying IPv6, like T-Mobile's 11+ million IPv6-only users who use their NAT64 platform.
I do agree that from a purist's point of view, it's not ideal, but it enables network operators to stay largely single-stack (on v6), while still facilitating access to the IPv4 internet.
Amazon only added it to EC2 instances a year or so ago.
Most corporate network and infosec guys I've talked to about it are dragging their feet as much as they can--network guys because if they don't have to have it, they don't want it, and infosec guys because it's one more attack surface, and is not as easy to enumerate as IPv4.
Personally, if it gets us back to old-school disintermediated communications, I'm excited about it. In the back of my mind, I fear the powers-that-be will come up with some bullshit to NAT the hell out of IPv6 as well. Disintermediation will de-rail quite a few gravy trains!
Now I pay more (like 35€/m instead of 20€/m) to get an IPv4 only connection.
Facebook already does this - everything is IPv6 only inside their datacentres, and the only dual stack devices are their load balancers at the edge. They had to do this because they were running out of RFC1918 address space to use internally for IPv4, and the traffic was already going through the dual stack load balancers anyway.
On the access side, mobile networks are also going v6 only. EE here in the UK (sometimes) only gives you an IPv6 network and uses 464XLAT to NAT you when you want to reach an IPv4 only address. They can do that because they know what devices all their users are using, and can whitelist recent versions of both Android and iPhone which have CLATs in them which makes 464XLAT possible.
Fixed line residential and business connectivity is much harder - laptops and smartphones will work just fine with IPv6 only, but people expect their games console or old networked print server to work, and frequently they only support IPv4. What's needed there is islands of IPv4 on their LAN and a 464XLAT compatible CLAT inside the customer's router - then the entire ISP network can be v6 only apart from a few NAT64 devices at the edge. I'm sure that will come, but it hasn't happened yet.
It will happen - mass adoption is inevitable IMHO. There are new internet users and services being added every day, and there aren't enough IPv4 addresses for all of them. It's either IPv6 and 464XLAT or IPv4 only with CGNAT. And CGNAT is expensive - keeping state for all those connections makes for expensive boxes with lots of memory.
IPv6 was a clean break from IPv4 with a lot of changes because the authors knew that there was a very high 'minimum cost' to any IPv4 replacement. Even if they only added more octets to the addresses, there were still billions of networking devices which would need replacing, millions of people to retrain to some degree, mountains of software to modify or rewrite, and a similar conscious decision to switch. If we had to go through this pain anyway, then the obvious choice was to go all-out designing a greenfield new protocol which solved as many problems as possible and which would last for as long as possible. That's IPv6.
IPv6 is here to stay. It's already 30% of the internet, and has industry-wide buy-in and backing. All OS' support it, Apple even requires apps to work in IPv6 only environments to get on the app store. New IPv6 deployments go online every day.
IPv6 will win. One day. The costs of keeping IPv4 around are high and increasing. ISPs are spending millions on specialized CG-NAT infra to keep their dwindling pool of IPs usable, in return for tremendous capital and maintenance costs, reduced performance, increased support burden from angry customers who had their app broken by CG-NAT. And anyone who wants to buy an IP address has to deal with the price - which just keeps going up.
v6's L3 model is pretty much the same as v4's.