Git is about data integrity. Improved correctness is extremely valuable here.
Rust can be injected into native projects because it has no runtime requirements. So here it's ideal and makes a true rewrite unnecessary unlike other languages.
Rust is creeping into system software as a wholistic replacement. It's very rare that a language can actually entirely replace C/C++. However it's discovering that the process is incredibly slow.
There are things Rust isn't as good for, but it's only a matter of time before those gaps close (mainly around specialised environments and targets).
I don't know if Rust will actually succeed in replacing C/C++ before something better comes along but the writing is on the wall. If you want to get in early on Rust, now is a good time.