You have nushell "the language" and nushell "the shell". You can still use bash, fish, zsh for your day to day shell usage. They are proven, rock-solid and super stable. However, for the kinds of tasks that nushell excels -- gluing together programs, doing simple analysis of the output of text oriented programs etc. nushell can be a viable choice. Here I'm emphasing nushell "the language".

Every language was a niche language once when the user base was almost zero. So I guess it depends on your personality and organization -- are you an early adopter ? Or do you like waiting until the tool/language has established itself ?

I would argue that nushell lets you write powerful scripts like bash. But it can be better than bash because it offers powerful constructs, patterns and primitives. I think nushell is here to stay.