Depends on a number of factors. I think GitHub copilot is reducing that trade off a bit more. If the average dev stays somewhere for 2.5 years (our average is quite a bit higher because I tend to think we’re good place to work) - how long are you willing to invest in them learning the new tech (and on top of the, business logic/etc)? The lower the investment number the less you’re willing to dive into rust sans specific technical reasons (which go and elixir would easily meet).

Separately, I don’t buy the notion that a language that has a bit more boilerplate is less productive than one with virtually none.