Something like this can't really make end to end encryption interoperable. There will be no encryption at the transitions between systems. Clients would have to use something that can work over arbitrary textual channels like OTR or PGP.
HTTPS works encrypted between multiple clients, servers and proxies without issues (mostly). There is nothing impossible about encrypted communication. It's just that all servers and clients need to work together to achieve this.
HTTPS is not end to end. End to end encryption does not require a server and could not use one anyway. Effective end to end encryption has to entirely happen on the ends.
