Privacy by necessity will use end-to-end encryption, as artifacts will end up being propagated on the network. This isn't however so easy for long-lived artifacts (eg. what happens if your key is compromised sometime in the future), and we will need things such as forward secrecy.
It's not 1989 anymore, we have proper cryptosystems now. I don't have a worked example but elsewhere in the thread someone, it sounded like a dev, mentioned it's being worked on. You can encrypt for certain public keys and then only those people can decrypt the contents.
