IPv6 has made enough progress that it's totally possible to run your network off of it, regardless of what everyone else is doing, and if all of your neghbors are using IPv4, it won't harm your IPv6 network.
Also, part of the delay in the switch to IPv6 is that some work is needed to ensure that home routers and IoT devices default to reasonable security settings, and the absolute worst thing to do is force them to switch first, and figure out security later.
The answer isn't to force everyone to use something before its ready; the answer is to address every impediment, so it's worth it for everyone to switch. Sure it's slower, but it's much better than making users worse off by switching, converting them to detractors instead of supporters.
Doesn't IPv6 hurt anonymity? NAT is annoying, but hides the number of devices you have. ISPs assigning you different IPs at different times at least provides some measure of identity resetting.
To say nothing of how easy it is to keep IPv4 devices confined the local network
Or am I missing something?
https://en.wikipedia.org/wiki/IPv6_address#Temporary_address...
NB: your useragent already sends enough info to effectively distinguish your from the other users behind the same ipv4 address
It's still an extra fingerprinting signal, and all things being equal you'd want less fingerprinting vectors. Otherwise you fall into defeatist line of "google already probably knows my interests quite well, so I might as well not bother trying to obfuscate my advertising history".
It's an extra signal that's basically impossible to spoof
>NB: your useragent already sends enough info to effectively distinguish your from the other users behind the same ipv4 address
???
User-agent provides very limited set of information. Two chrome users on windows have the same user agent. Unless you think everyone in a household uses a different browser/OS combo, user agent isn't enough to distinguish users. You'd need to get into canvas/webgl fingerprinting to uniquely identify a device, and even then that can't distinguish identical devices (eg. two people using iPhone 16)
Yes, but it's value to the interested party is minuscule, precisely because it's not a permanent and distinguish enough signal. They already have a lot more stronger signals so ditching ipv6 for ipv4+nat would not improve your privacy in any meaningful way.
> User-agent provides very limited set of information
Yes. But if you have two 'users' in your ipv4+NAT network and the one is using an Apple device while the other uses some Android device - you already, without providing any 'extra fingerprinting signal' like a ipv6 address, gave a signal strong enough to distinguish between those users.
> You'd need to get into canvas/webgl fingerprinting to uniquely identify a device
No need for that to distinguish between different users behind a NAT. Your cookies, your UA, your logged in accounts, your requests to fonts.google.com for a fancy website - they all give enough information to do that already. I remind the original point about CGNAT - it's massive amount of users who are intermingled on the same IPv4 pool and even sometimes change the used address in process.
Ad platforms already need to work with an 'non-identifiable' IP:port combo datapoint in the first place, so they do their work to identify you from the every breadcrumb they can leave on your device.
And by the way, if you have any 'cloud enabled' app on your device the big boys already knows where and who you are. Eg: any app what uses Firebase, or Location APIs or bazillion of other 'cloud' things...
The related flip side, though is that NAT44 isn't a privacy solution, it's an over-reliance on the Pigeon Hole Principle and hoping that's enough privacy. An advertiser already has way more data to work with than just IP Address: os/browser combos, user agent strings, cookies, timing habits (device hits website x first thing in the morning), and so much more. NAT44 is absolutely not sufficient for privacy. It is a defense in depth sure, but huge scale difference of IPv6 is a different defense in depth with similar Pigeon Hole Principle properties, it's not necessarily a loss of depth on its own.
I worked on network management software, the kind of software that runs on out of band networks that are unlikely to ever need IPv6. In the beginning IPv6 was a required feature for sales but it was accepted that no one was going to use it so little effort was put into testing it. More recently, it HAS to work. It is being used in anger internally in large telecoms companies.
I expect adoption to proceed at a glacial pace until some tipping point. Consumer ISPs will be the last to adopt it.