Is even the majority of users of desktop web browsers actually using adblockers yet?
Adblock Plus on Firefox shows a bit short of 20 million users, while Adblock on Chrome says 'over 200 million downloads', whatever that means in number of users. These numbers don't suggest a majority. (I don't think assuming over 500 million desktop users is crazy.)
Given that iOS is about 20% of total mobile users, this feature will probably make little to no difference, it might be a couple of % of those 20% of users, at the very best.