Currently, I am envisioning posting `mumble:` links in matrix channels, maybe pinning the message, together with a bit more info in custom events.
If a Matrix client doesn't integrate mumble client functionality, you could still click on links. If it does, there could be some further integration with authentication.
It's a post by a very recent account, that didn't write that much to begin with.
With that said, screenshots look similar to the Element Matrix client: https://community.teamspeak.com/t/wishlist/1436/283
Even if TS5 was to be based on a Matrix client, that doesn't imply it supports the official Client-Server nor Server-Server APIs.
I've argued that Matrix was a good fit for integrating into Mumble, I am still of that opinion.