Hipchat can grow a lot, I really think every organization, tech or not, will eventually start using a tool like hipchat or slack.
That's the only reason to use Hipchat today, and the Slack experience is an order of magnitude better.
I think Slack put some pressure on the Hipchat team but there is plenty of stuff that is highly problematic for how Slack is set up at the moment. In particular even for small teams it can become incredibly hard to see what's happening and the integrations either spam too much or are too useless once it becomes a bit more crowded in a room.