This seems like it will have the opposite effect: unmask folks trying to use a proxy/VPN by having them go through a Chrome proxy first. It'll also keep IP data only available to Google for tracking purposes.
Probably isn't a good time to being doing this and revoking third party cookies while under antitrust investigations.
We don't have any details about how it works, but it's possible to implement this in an anonymous way. See my other comment: https://news.ycombinator.com/item?id=37551708. Whether google actually does this is unknown, but considering that google is voluntarily disclosing this to the public I'm willing to hold off the pitchforks until we get more details.
But is it possible to implement this in a way that the user can rely on beyond google saying “trust me bro, we implemented this right and have no ability to turn this off without you knowing about it even if we'd rather you not know”?
Probably isn't a good time to being doing this and revoking third party cookies while under antitrust investigations.