Despite the name, third-party cookies did not vanish on a single date: Safari and Firefox block them by default, and Chrome kept them after reversing its deprecation plan in April 2025. The shift is really about their declining reliability, which is the structural reason first-party data, identity resolution, clean rooms, and server-side tracking matter more now. The DMP model depended heavily on third-party cookies; these approaches depend more on first-party identity, consent, and controlled data sharing.

In practice

Treat the post-cookie shift as a reason to invest in first-party data and durable identity, not as a temporary inconvenience to route around.