"Facebook has a vested interest in IPv6 as no NAT means tracking users more effectively."
Presumably IPv6 ISPs will offer NAT capability precisely to avoid that tracking. The article mentions globally routed unique addresses which are changed every day.
I will only go to IPv6 when a reasonable ISP offers that privacy. My current ISP always allocates a new customer a fixed IPv4 address - which is unnecessary for my purposes. I would have preferred it if they had an option of a dynamic one.