PGP is secure and usable if you can manage keys. The issue with the adoption is not much the protocol itself: Average user has no idea what is (asymmetric) enc

PGP is secure and usable if you can manage keys. The issue with the adoption is not much the protocol itself: Average user has no idea what is (asymmetric) encryption and will never manage keys; the process has to be automated and be provided by default. To use PGP, you need GnuPG, and, say, Thunderbird+Enigmail. These are the barriers to adoption not the PGP protocol (which still could be updated). Automating key management and encryption is what ProtonMail and other apps are trying to do. Google could include PGP in Gmail and it will be widely adopted over night.