If your location is assigned a /48 you can then set up over 65,000 subnets with 2^64 possible endpoints in each. My iPhone spoofs the MAC address each time it

If your location is assigned a /48 you can then set up over 65,000 subnets with 2^64 possible endpoints in each. My iPhone spoofs the MAC address each time it connects to WiFi, so support for changing your /64 is not going to be a challenge even with consumer devices. Whether we lose this ability or not is another question (but they could easily make the same requirements of “hard device uuid” on IPv4 if they wanted. These are laws and regulations after all, not technical limitations). If anything IPv6 gives you an even greater amount of plausible deniability because like you said you could be running a vpn with a billion different devices connecting to it. IPv6 just means your laptop could have an internet routable IP associated with it. You can easily change to one of the billions upon billions of possible addresses that your assigned prefix will give you (just like you could have something like 10.0.0.0/8 with millions and millions of addresses behind your internet routable IPv4 address. Your ISP will turn you over all the same if the authorities ask who that address belongs to.