I have had a way that will work for a long while and am beginning to get it deplyed. A lot of the delay has been because I do not want this privacy friendly method confused with the Phorm method which is rather more direct.
The step that comes next is to try to segment and target based on proper evaluation in privacy friendly way. The step after that is to see if we can move from buying and selling online display advertising in terms of the media and move it to selling solely in terms of its effectiveness. That is to say if I am measuring the effect, in store and online, of the adv ertising, then that should be what is used to charge. If you are creating a 5% uplift in sales then you get a percentage of that. If the unplift is zero you get a percentage of nothing and so are paid nothing. If the uplift is larger you get more money.
Clearly there will be exceptions to this. If I have a bad product that no one will ever want to buy I am not going to be able to buy advertising on thos basis. Also not eveything is about sales.
Perhaps I am advertising the disadvantages of smoking because I am a government or a charity. That is not going to create additional sales and cannot be charged in this way. Still I am moving towards this goal and will see if there are related goals that arise for different industries.