So what you mean by niche is actually popularity, and not a specific application area?
Fortran has a niche: numeric computing in scientific areas. However, even Fortran is not your grandfather's Fortran 66 or 77 any more. I had a semester of the latter once, as part of an engineering curriculum before switching to CS.
It supposedly has OOP programming in it, and operator overloading and such.
I don't know modern Fortran, so I wouldn't want to look ignorant spreading decades-old misinformation about Fortran.
Implementations of Lisp are no more niche than other languages with managed run-times.
Lisp has been used for even operating system development: Lisp code taking interrupts, and driving ethernet cards and disks and so on.
Which member of the Lisp family are you talking about, and what do you think is the niche?