Even as several high profile initiatives have come and gone, publisher ad alliances are getting a another look for their ability to offer combined scale and a one-stop shopping experience for buyers, especially when third-party targeting will no longer be possible. How will impending cookie changes affect the digital identity ecosystem and how should publishers get their first-party data together, for themselves, and to potentially offer better second-party data to alliance networks in future? Here's a fascinating discussion on the challenges and lessons learnt so far.