In fact, as far as I'm aware of, this is also how the situation plays out de facto in most (all?) European countries.
> The rights holders have effectively said "you can watch this for free as long as we get the ad revenue".
The key lies in the word "effectively" here. They may have said and even meant that, but I am unaware of a legal mechanism that would actually allow them to do this (in Europe). The only way I can think of accomplishing this would be to make the content available under a dedicated, bespoke licence, akin to how GPL works, and even then I'm unsure whether it would be enforceable. TOSes, generally, are not.
> It's not hard to predict that's coming, especially in Europe given Article 13 last year.
This is wrong. Article 13 regulates content hosts (in this case, Youtube), not end users. Hence, Article 13 has no bearing on ad-blocking software.