> If the value per ad decreases, services will need to display more til the user generates enough value to support the costs they incur.
What they need to do is to find a way to pay their bills. If ads allow them to do that then it's great (maybe non-personalized work well enough? Or contextual targeting, as others have suggested in this thread). If users cannot stand the increasing amount of ads then they will stop using their service. Or maybe these companies can adopt a mixed model where people can pay to not see the super intrusive ads, and everyone else gets the ads?
If the value per ad decreases, services will need to display more til the user generates enough value to support the costs they incur.
If TV was able to cater ads to individual viewers then ad breaks would be a lot shorter.