The main thing that discord did was combine voice with the chat side of things, and with per user chats and history. A lot of people don't know that mumble has a pretty decent html capable chat, but it's the history searching, dynamic rooms etc that set discord apart. Mumble still has the superior voice capabilities (simultaneous multiroom, easy permission, hierarchical, etc)
I have put most of my hope in mattermost to do murmur integration to solve this problem.
In the meantime I find myself considering trying to get everyone back on irc+mumble.
edit: Also, just have to say I bet the gov loves having a single place to send all those NSL's... cough hint cough