This is just an overall idea I was thinking about when working on the 4.1 XMLRPC Epic (MDL-70889).
We certainly could consider moving away from xmlrpc as the underlying protocol for the MNet stuff. Surely, also, nowadays, the "built-in-home" encryption / wrapping of all messages is not needed anymore and we can rely on pure https/ssl e2e communications.
Also, applying to it new authentication / authorisation techniques or whatever. In fact, maybe, we could make "MNet 2.0" to wrap / work the same than any "Moodle Net" specification that can be defined).
Ideally 100% in a BC way (over some versions), guaranteeing that old and new sites can continue working together without problem.
That would lead to a way easier MNet implementation, clean, easy to debug and to build new features on to of.
To dream is cheap™
Ciao
PS: Have added the "MoodleNet" component to this issue just to know what people working on it thinks about any possible relation, or if there is any docs about the protocol used by or if, maybe, it doesn't make any sense.