Python numerical computation modules are being written in C / C++ / Fortran anyway. Of course, Rust is good here as well. What remains is the glue mostly (if done right).

So the suggestion to replace everything with Rust (or C or C++) will lead to same things will be rewritten / reinvented like Greenspun's tenth rule states, citing from Wikipedia:

Any sufficiently complicated C or Fortran program contains an ad hoc, informally-specified, bug-ridden, slow implementation of half of Common Lisp.

The key is as usual to use the right tool. Not everything is cost efficient / convenient / practical to do in statically typed language.