Audience is only part of the equation, arguably not the largest part. How many content creators use adblock? The big ones already know how completely meaningless ad revenue is because youtube doesn’t pay them enough and they are already aware of how easy it is to block ads. Also they’re more likely to be using youtube on a desktop because they use one to create, and they also are more aware of the alternatives like revanced. A lot of big creators have spoken out over the years in favour of adblocking.
If youtube makes it impossible for creators to use their own platform they’ll leave in droves, and they will have the voice to encourage their audience to follow. Youtube isn’t the main voice on their own site, the creators are.
Another thing this will impact is the ability for creators to collaborate, since they would have to watch others’ ads in order to see their videos.
Once that happens, the audience will naturally follow. That’s how social media sites have failed in the past. They’ve pissed off the power users to the point they finally left, then the content declined, then users followed.
Youtube is making the same mistake all capitalist entities do, of mistreating the people who actually make the product they’re selling. It’s a fundamental contradiction that only leads to decline in the end, it’s just a matter of when. This may not be the straw that breaks the camel’s back, if this isn’t it, then something down the line will be.