Slack is extremely expensive for large "community" chat rooms. If you could handle a several-thousand user room and offer full functionality for a fraction of Slack's price you might have something that could get some traction.
- Large open source projects
- MOOCs with many students
(Taken from discussion of this post from yesterday):
May be some app for easy find right group chat (Android global group, hacker news group, SF Local Tech group, etc...). May be someone know such apps? I try to find it, but no one tries to implement this.
It sounds to me that this use-case is more like a public forum than a chatting solution.