I think Nim is in the sweet spot for it. You start with basically OCaml, which is already a great start, add some knobs for tweaking memory management, some for high performance, and you're in a great places. Compiling to native and to JS allows you to do web, cli tooling, applications, high level gamedev. Fast compilation is important for scripting, high level gamedev, exploratory programming, scripting. High performance allows you to do low level gamedev, deep learning, stuff like that. Being bootstapable from C and compiling to it with the memory management tweaks opens you the world of embedded.

There's also the fact that not all language are perfect. If they all are, the general language would always lose to the specific in every niche, so you need to do different things for the general to be worth. But languages aren't perfect, and you could prefer the general language even in niches.