They can certainly, say, ban Apple and Google from hosting such P2P apps in their app stores, then any such apps are useless to most people. They could also go

They can certainly, say, ban Apple and Google from hosting such P2P apps in their app stores, then any such apps are useless to most people. They could also go after developers, forcing them to either install backdoors or shut down - see what kind of laws Australia passed about that, as an example. Remember they only care about most people, they don't need to get every last one of us. Their point is to make default methods of communication unencrypted.