> Surely "nails in the coffin of C/C++" does not imply an all out effort to rewrite all this existing and working software from scratch.

Or you use the evolutionary approach: remove the unsafe part from C/C++ bit by bit. And do code migration (Carbon style) when you can do it. This is what some C and C++ committee members try to do and fortunately they are there.

Because that is way more likely to happen in a reasonable time frame (next 15 years) than rewrite Chrome, Linux, OpenSSL, Office and all the other 10 of billions of proprietary code we have around in Rust.