[MattJ100]

A mere protocol will never "hit the bigtime" without some compelling (non-protocol) reason. It's unfortunate that businesses choose to build silos time and time again, but that's where we are - it's not an issue that can be solved at the protocol level.

Should this be fixed (e.g. through regulation), XMPP is absolutely a sound choice - given, as you say, its 20 years of experience, evolution and deployment track record.

[kitkat_new]

honestly, given the current adoption, growth and state of the ecosystem, I don't think it is.

In theory, you could achieve with it what Matrix achieves, but it would probably be more feasible to start from scratch - like Matrix did

That said, I see how it currently has advantages when it comes to resource consumption as well as internal deployment to centralized services.