Earlier quoted context omitted.
It's the part in the lower 64 bits that does not change as one moves around changing prefixes that worries people. And of course ways to pseudo-randomize that already exist, as mentioned already in this very discussion.
for the last 10 years or so, every single OS out there randomises the lower bits by default and even rotates it every few connections. The thing that remains static is the prefix you got from your ISP but that works in exactly the same way as your v4 address you get when you connect.
Not in the scenario actually under discussion by okket here.