Well, that’s ominous. Presumably the plan is to close source Chrome or do some DRM thing to prevent sites from rendering if the Privacy Sandbox has been tampered with?
Great.
"By undermining the business model of many ad-supported websites, blunt approaches to cookies encourage the use of opaque techniques such as fingerprinting (an invasive workaround to replace cookies), which can actually reduce user privacy and control."
"At the same time, we’re developing techniques to detect and mitigate covert tracking and workarounds by launching new anti-fingerprinting measures to discourage these kinds of deceptive and intrusive techniques"
("Mitigating workarounds: As we’re removing the ability to do cross-site tracking with cookies, we need to ensure that developers take the well-lit path of the new functionality rather than attempt to track users through some other means. ...")
After initial dialogue with the web community, we are confident that with continued iteration and feedback, privacy-preserving and open-standard mechanisms like the Privacy Sandbox can sustain a healthy, ad-supported web in a way that will render third-party cookies obsolete. Once these approaches have addressed the needs of users, publishers, and advertisers, and we have developed the tools to mitigate workarounds, we plan to phase out support for third-party cookies in Chrome.
(Disclosure: I work on ads at Google, speaking only for myself)