For me, IPv4 doesn't break the privacy barrier, IPv6 blasts a huge hole straight into each and every household, office and IoT device on the planet. No, privacy fixes put into IPv6 do not work.
Until browser fingerprinting is addressed, there will be no real privacy.
What exactly is the problem with the privacy fixes that were put into IPv6? Why don't they work?
You are correct that this isn't a big issue. SLAAC addresses are generally changed fairly frequently by the OS. As for stateful DHCPv6, well I turn it off for both this reason and the fact that Android doesn't support it.
You can change that, of course, and switch addresses every minute if you want to, but I do find the default a little high.
Identification to the level of IPv4 can still be done with IPv6 by using the /64 where you would previously take the /32, but with IPv6 you also get identifiers from within the network as well.
With how much IPv6 space is available, I'm not sure why SLAAC-based networks don't just assign different IP addresses to different use cases. I can see this becoming a problem on large company networks, but in home networks you could generate a random IPv6 address every hour for every website you visit and still never run out of address space.
Operating systems aren't exactly geared up for per-application outgoing IP addresses, and perhaps handling tens of thousands of IP addresses will bog down the kernel somehow, but in terms of privacy protection we could be doing a lot more than what IPv6 Privacy Extensions are doing right now.