Replace your example with assembly and C. According to this, C can't replace assembly and assembly can't replace machine code, which is an absurd statement.
No modern development of OS is done in assembly only.
As a poet once said - "Perfect is the enemy of good".
Rust never aimed to replace all of C/C++ forever, everyhwere. That's nigh impossible. Much in the same way, it's impossible for ASM to replace machine code or 386 processors to replace Commodore 64 or Analytical engine. There will always be some shop that programs in ASM/C/C++, like there are shops that program in COBOL.
Rust point was - to replace C/C++ in domains that require safety and speed.
Replace your example with assembly and C. According to this, C can't replace assembly and assembly can't replace machine code, which is an absurd statement.
No modern development of OS is done in assembly only.