I've been wondering when the day would come that youtube simply interleaves ad content into the videos and bypasses adblock. Perhaps they haven't done it in the past to avoid user backlash. Now they can simply say "upgrade to red to get back to an ad free experience".
IMO You underestimate the tiny amount of effort to the large payoff with adblocking.. What will come along is an adblocker which skips around the ad parts of the video automatically.
I'm assuming the ad is seamlessly part of the video - probably there will always be some way to determine that there is an ad but also there would end up being an arms-race about it so I would expect it would prohibitively expensive for ad-blockers to block ads that are just part of the video being streamed.
Remember Youtube's object is not to get rid of ALL ad-blockers, it is make the use of ad-blockers really uncomfortable for the MAJORITY of the internet users.
