I just wanted to clarify that I specifically called out how easy it is to hire for. A lot of developers are pretty quick when it comes to adapting to a new language and there are virtues that lean in favor of a language being easy to pickup: sharing a paradigm with popular language, sharing conventions with popular languages and good documentation.
I have yet to work a day job in Rust, but I've worked in Java, C++ and Go so I'd be quite confident applying to a Rust position as long as it wasn't specifically security focused... I would be less confident in how quickly I could pickup Prolog - I think my brain works well for the nuances of the language but I'm less certain.