There is not a migration from reddit to hubski. What? Let me put it in national terms reddit has 43 million users that is 3 million people more than Argentina. There are less than 6000 accounts on hubski that is about the same as Saint Pierre and Miquelon ever heard of it? To rephrase it in a way that Americans can understand if reddit is America hubski is the Cayman Islands.
What we are experiencing here is not a symptom of reddit's decline but and testament to it's strength. In my estemation Hubski has had a period of growth because like anything else that makes it to reddit's main page we got a hell of a lot of hits.
Continuing the national metaphor it is as if Brad and Angie visited the Caymans, raved about their trip and some people planned their vacations based on that.