> But many IT departments require on-premise hosting, which Slack doesn't offer.
Less and less IT departments do that now, since so many things move to the cloud. When you have all your stuff in Gmail and Google Docs already, having Slack is a no-brainer.
But many IT departments require on-premise hosting, which Slack doesn't offer. Users don't care about open standards, but maybe their sysadmins do. If IRCv3 can capture this audience, it has a chance to co-exist with Slack.