Does this finally get away from the problem that XMPP had in the old days, where the usage model was tightly bound to the domain model, so each domain would have one and only one XMPP server (plus possibly a fallback) and if you aren't the domain administrator then you can pound sand?
It was pretty much impossible to run your own server for fun unless you registered a domain or two because of the serious business logic baked into the design of the protocol.
Ages ago when I was working on a replacement for IRC for an organization that needed to decentralize its servers because they had a lot of users spread across the world behind iffy internet uplinks but all on the same domain this was a huge headache. The old IRC system worked really well for them, but some of the higher ups were upset because it wasn't "enterprise quality" and thus shouldn't be on their network.