I know python is not suitable for things like microcontrolers, make drivers etc, but besides that, you can do everything using python, companys get stuck with speed optimizations for real hard time system but does forget other factors which one you can just upgrade your hardware for speed proposes in order to get your python program fit in it, if you think how much cust can the company have to maintain a system written in C, the comparison is like that:
for example: 10 programmers to mantain a system written in c
and just one programmer to mantain a system written in python,
with python you can buy some better hardware to fit your python program, I think that low level languages tend to get more cost, since programmers aren't so cheaply than a hardware upgrade,
then, this is my point, why should a system be written in c instead of python?