Google won't implement this spec. Currently, they're legally not allowed to, because advertisers called in the industry watchdog, asserting that without third p

Google won't implement this spec. Currently, they're legally not allowed to, because advertisers called in the industry watchdog, asserting that without third party cookies to stalk users, they could not compete. Google extended their privacy sandbox, opened and closed it, talked about it, and eventually backed down from their plan to block third party cookies ASAP. Maybe Chrome can get away with "the spec says it, sorry advertisers" but I doubt the courts will accept that.