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.