The problem with having a niche is that nobody can replace you so you're stuck working on the same thing forever

What if you really like that niche? That said, with Clojure I can do React.js, Node.js, JVM and, as of recently, even Dart/Flutter development. Within each of those there's a vast array of things that can be done as well, so it really should not get boring anytime soon.

Yeah, cljfx is nice for desktop stuff. The data science ecosystem is actually coming together slowly with the tech.ml ecosystem. Deep Diamond is super clean and fast for low level deep learning stuff. And then you have Babashka which can give you a ton of value around scripting and automation. Really hard to build and scale a team around all this though.