I think when people talk about functional programming being used more in industry, they don't imagine it replacing Java or Python as the lowest common denominator language everybody uses. Rather, they imagine either small companies or small teams within larger companies using functional programming to be more productive.

So the sheer number of people using functional programming may not be very high even if functional programming is making inroads into industry. Now, I don't know whether functional programming actually is making inroads into industry or not, but my impression is that anybody relatively good at it could find a very nice functional programming job fairly easily.