Mumble is a much better experience than Teamspeak, at least in my experience.
* Persistent chat
* Multimedia chat (Emojis, resized images, etc)
* Camera streaming/game streaming (MUST HAVE these days)
Additionally, if there were "mumble multi-server management" that allowed a host to spin up other servers quickly, third-parties could skim off Discord. There is no loyalty to Discord IMO, it's just so damned easy to use.
Man, that would be pretty sweet though. Someone could cobble together an unholy Mumble + Mastodon beast of privacy-respectful gaming communications