Back in 2015, I predicted that once ad-blocking became common, we would be faced with server-side tracking:

You know what will happen once most of us install ad-blockers? Server-side ad SDK's, that's what. Unblockable ads, unstoppable tracking. https://twitter.com/TobyKurien/status/628227819076775936

Well, it's here in the form of Server-side tagging in Google Tag Manager, and it's easier than the SDK I predicted. #adblock #privacy

Server-side tagging
https://chromium.woolyss.com/f/HTML-Google-Tag-Manager-the-new-anti-adblock-weapon.html