The whole PRISM scheme worked because people supposed the government respected their privacy. Now that it's been proven false, I expect people to use local encryption schemes, were third parties can't give a key they don't have. I expect people to become careful about which certification authority signed their SSL key, and to use self-signed certificates whenever practical. Targeted spying will remain possible, but indiscriminate surveillance PRISM-style would become impractical.
Unless they know how to crack TLS, but we have no reason to believe this as of today.