You already have end-to-end encryption: Start a Tor relay and add onlynet=tor to your bitcoin.conf. Now this will encrypt your connection without relying on a server-issued certificate, as there is no centralized server in this case.
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I know we already can use Tor (or even I2P) to perform end-to-end encryption. But it's not part of rule which handle connection between nodes and not everyone would bother setup and use Tor/I2P.