Discord didn't become big because it's Discord, but it's because they made a place where communities were able to be formed, and then people CAME and FORMED communities.
Even if a FOSS clone of Discord sprung from thin air today, 99.9% of the communities you could not convince to move.
A place needs to exist, then people need to start making communities there that other people WANT to join. Then it can grow from there.
That's how communities get built. A few people start something, somewhere. Then they convince individual other people to join. By asking around, advertising, whatever. It's hard work, and it doesn't happen overnight.
The discussion about IRC, Mattermost, Slack, Jits, XMPP, what-fucking-ever, doesn't matter. Take a few of your friends, start on any one platform you like. Hell, host a webforum ffs. If you really want to ditch Discord, that's how you form a new community.
But don't make the mistake to expect or try to convince your existing community to move over 1-to-1. You'll be disappointed.
