Pundits all over the InnerTubes are predicting that Apple's support of ad blockers is the death of ad-supported Web sites. Maybe so, maybe not. But I have not heard anyone discuss the inverse: the proliferation of ads was killing ad-supported Web sites.
The increase in ads has been a kind of drip-drip-drip....barely noticeable until it seemed to reach a preference cascade for me. Some Web sites had so many ads popping up, over, under and around the content that the site was pretty much unusable on smaller devices like a smartphone or small tablet. So I reluctantly stopped going to those sites unless I was on a desktop.
So it is not really about ad blockers at all. It is really about how content--good content--is going to be supported in the future if there are fewer ads.
The other thing I don't see much discussion of is the supply and demand problem. That is, if there is an infinite supply of ads and ad space (on the Web, this is pretty much true), then the value of placing any single ad approaches zero--basic economics.
What the ad blockers may accomplish could be a return to sanity, with fewer ad spaces on Web sites, and advertisers willing to pay more to get access to that more limited space.