Hipchat/Slack bring a lot more to the plate than just text chat, I think there is room for a customized IRC system to fill that gap, but it would take a lot, including native apps, notifications and tight control over granular settings, as well as centralized permissions for larger teams.
Of course, nothing is one size fits all. I doubt slack or hipchat could supplant IRC, and I doubt they would try. I was addressing the parent comment - I think the same goes for IRC, a new interface for IRC doesn't negate the niche filled by Slack and Hipchat.
