I love IRC. Have you used Slack, though? Think about why the Hitchhiker's Guide to the Galaxy was popular: it was friendly and non-threatening. Same with Slack, really: even if it functions like IRC, it looks absolutely nothing like your favorite IRC client. Anyone in the company can start using it with basically zero training. It's pretty, brightly colored, approachable, and discoverable. HipChat could have won that space but their UI felt like they wrapped IRC in Java and called it a day.
Slack's made a killing off an IRC-alike that non-technical people genuinely like using. Microsoft seems corporately unable to improve upon the things that made Slack take over businesses by storm, but there's no technological reason they couldn't do it. There's a lot of room in this space for someone willing to put a premium on user experience.