My opinion on this is that traffic is only capable of so much..
How many TGPs are there?
How many new affiliate programs arise there every day?

Its a fact that daily Internet is getting about 35000 new users across the globe, but the old users become more and more educated about the sources of their favorite stuff. So no wonder we are facing a problem.
Adult industry is no longer an easy money maker, it is a business. And if you don't take it seriously, you loose, just like in every other business..