As somebody who programs in both Python and Rust (and likes both languages) I think Rust's place would be parts of the code that have to be fast, and that you want to get right.

Calling Python code from Rust or Rust from Python is totally doable, and there is in my view no reason why you shouldn't use both in the use cases that suit them.

And the speed part is serious. Some guy once asked for the fastest tokenizer in any given language and my naive implementation came second place in his benchmark right after an stripped down and optimized C variant.

So using Rust for speed critical modules and interfacing them from easy to use Python libraries isn't exactly irrational.