So what happens when the major mobile networks decide to stop allowing PGPP to use their network?
I seen this happen before. I used to use the "Private Buyer" Payment service to anonymously pay for services privately. They had issues with payment processors preventing their payments from going through. I gather largely due to the privacy aspects of the service. That was in the early 2000 and I think the went out of business after 3-5 years.
It's true, they could. The one thing that is perhaps helping at this moment is that they've come under scrutiny for their (bad) privacy practices -- both from the media and from the FCC. Ultimately we see privacy as a layered problem, from a technological standpoint and a social standpoint -- we need layers of protection across the network and software stack and also a combination of policy, technology, and user behavioral changes.
I seen this happen before. I used to use the "Private Buyer" Payment service to anonymously pay for services privately. They had issues with payment processors preventing their payments from going through. I gather largely due to the privacy aspects of the service. That was in the early 2000 and I think the went out of business after 3-5 years.