Ask HN: Should I learn a niche language or something more employable?

I have been doing iOS development for a few years now and would like to branch out a bit professionally, specifically into cloud web applications. I work on personal projects in Clojure, Haskell, and Go in my free time and I really enjoy languages on the static/functional/concurrency-first side of the spectrum, however I'm afraid to commit too much time to them since there are barely any jobs for them. I'm also concerned about how closed off and proprietary the iOS ecosystem is. I'm still fairly early into my engineering career, so I have a few questions about how to balance learning these paradigm shifting languages vs maintaining an employable repertoire of skills 1. Ideally I would like to dive deeper into Go. Do you think that there will be more jobs available in a couple years for Go? Could I get hired doing ruby on rails if I mostly have Go experience? 2. Should I just learn rails and then learn more obscure things later? This seems to be the de-facto web application framework with the biggest community and number of jobs. 3. Should I just continue working professionally on iOS, learning whatever I think is most interesting on the side without regard to practicality?