AdBlock basically works by blocking inline ads loaded from offsite - eventually someone is going to figure out how to get around it.
And as far as "too intrusive", that will only last as long as people let it. It'll be the "slowly boiling water" technique, adding more and more intrusive ads slowly enough that there won't be an immediate backlash.
Any company wishing to create content will have to figure out how to monetize it somehow, or else they'll have no reason or ability to create/provide the content in the first place, and right now, the current ad model just isn't enough for the level of profitability that traditional media are accustomed to. If YouTube, one of the most popular sites on the planet, can't come up with enough ad revenue to be profitable, the current status quo just isn't enough. Either they will need to scale back their site, or add a massively increased volume of ads.