Ad blocking users won't reduce the entire ad revenue that is flowing through the system.
From the perspective of a company this is different of course - a company can increase revenue by maximizing the number of ads shown to users. But when you look at it from the perspective of the entire system, the more users are forced to view ads, the less valuable an ad becomes, so it's a race to the bottom.
The biggest problem is that ads are the wrong solution. In earlier times, many services that operate for free now were primarily paid services - paid voluntarily, which is based on respect and human dignity. And the ads were just printed in paper form, so there was a limit to how much money you could extract out of it. Ads had their place, but were limited in their scope. Publishers of paper newspapers would have never thought to maximize revenue by forcing users to actually look at an ad, because there was no technical way to do it. Now they think they are entitled to be intrusive, and to control user behavior while legally giving away something for free without any legal obligation for readers to return anything. So those who benefit from ads resort to moral pressure.
They have developed feedback systems, and the feedback systems are carefully designed to extract as much money out of people with no regard for anything else, which is dehumanizing, and this means ads (like all systems that use psychology to manipulate behavior) are actively destroying what makes us human.
They will only stop once the ad system has been dried out, and when that happens we finally may get meaningful content and journalism again.
