Selling out
It seems iOS 9 ad blocker, Crystal, will allow some ads to go through for a fee. From an article on the Wall Street Journal:

Mr. Murphy said he has taken Eyeo up on its offer, and plans to implement an option within his app whereby “acceptable” ads will be displayed to users. The feature will be switched on by default, Mr. Murphy said, and he will receive a flat monthly fee from Eyeo in return. Mr. Murphy declined to disclose the fee, but said he expects to make less money from Eyeo’s payments th … ⌘ Read more