Huge amounts of it, yes -- particularly since the anti-floc people (which, to be blunt, I'm not in love with, particularly Google just deciding to do this on their own) tend to also be in the break 3rd party cookies camp.

With respect to eg brand advertising: even if you get past an inability to measure impact, once you break most of the ad infra, ad buyers simply aren't going to negotiate / buy with small sites. It's not worth their time or money. Small here is probably less than millions of uniques per day.

With respect to direct response advertising, you've mostly lost the ability to track a conversion. So it becomes pointless.

The advertising before extensive tracking was a different time: way way less money, way fewer ads, way less ad blindness amongst viewers, way way way fewer publishers, etc.

Will some advertising persist? Absolutely. eg the branded / source trackable referral codes that podcast advertising uses. But there will be an enormous falloff in dollars pointed at publishers.

And to be clear, I'm not a fan of 3rd party tracking. But we should be deliberate before we end the ad-supported internet.