I don't know. I think there's room for a high-end niche shop that only deals in functional languages, for example. I see enough data now that 1 line of functional = 4 lines of Java/C/Go for the same amount of work done, to think that perhaps, SOME trendy technologies are actually worth their mettle.
I think the real limitation is not jumping on trends but managing cognitive load. That is your real limitation, the capability of the programmer-mind to fathom all the states their code can get in. To optimize towards that, you have to pick technologies that force the least amount of cognitive load on the developer. Functional languages such as http://elixir-lang.org/ seem to accomplish this (according to those who have switched to it and blogged about it, example http://mattscodecave.com/posts/elixir-for-pythonistas-pt1.ht...). In the javascript space, Elm seems to accomplish this. http://elm-lang.org/
But lastly, if you pick the right technology, you might naturally get access to a pool of very high quality developers, the type who are already interested in that very technology.
I don't get the point of hiring "Java people" and whatnot, anyway. Polyglots are the way to go.
The thing that made Paul Graham a thing was his use of Lisp to edge out his competitors at the time. The fact that Viaweb was later rewritten in [whatever it was rewritten in] is irrelevant. That's my final point.