> do you really think Google could get rid of third party cookies tomorrow and not get sued out existence?

Considering that ad blocking extensions still exist, yes. The browser (user agent) is supposed to act on the behalf of the user, not the remote server. It's not required to use cookies, display ads or run malicious code.

On what grounds would an ad company sue Google for a change in Chromium that enhances the user's privacy, while they can still display ads (just not track the users as much)?