Yahoo escalates war on ad-blockers--by keeping people out of their own e-mail

I don't disagree; ad-blocking will get tougher.

First-party ads won't be trusted by the advertising industry, since it's "easier" to commit click-fraud. First-party ads for the originating site itself were never really the target of ad-blockers in the first place. (I mean, if you're surfing Amazon, you probably want to hear what Amazon has to say about Amazon.)

Third-party ads will always be easier to spot.

Finally, at least until advertising becomes thoroughly intertwined with content, it should be possible to block ads based upon their position relative to main content blocks. I.e., switch to blocking ads based upon behavior, and not URI/DOM regex.

Edit: I should clarify that, unless you're a major publisher, you won't have the skills necessary to participate in the ad-blocking war. There will be more developer mindshare given to the ad-blockers than your minor site can afford. Sure, there will be public or private anti-ad-blocking libraries--but which do you think is more likely to be up-to-date?

I was actually thinking about this a while ago, but I couldn't figure out how to get around community-reported, site-specific element-blocking using CSS selectors (structural selectors, not id/class selectors, which can be easily defeated by randomization). You'd have to periodically change the placement of your ads and/or the layout of your site, and that's not really viable as a long term solution.