what's to stop using existing tech like ssh, private VOiP, Tor, and VPN?
(what it says in the topic)
there are so many existing protocols capable of end-end encryption that it's pathetic to even TRY and stop it.
If FB installs a back door, then "an app for that" _WILL_ happen because someone like me will write it. Then Faece-Bitch won't be able to insert themselves and monetize your conversation, so they have a vested interest in NOT having back doors.
besides, there IS ALREADY a vacuum for a decent PRIVATE end-end encrypted peer-peer application. All it needs is a protocol (like torrent trackers have) to find the peers, along with some dedicated servers to connect the ends. Then the rest is peer-peer including the encryption, no 'man in the middle'.
If done properly there won't be a record of any of it, other than the IP addresses of people identifying themselves to the service.