This comment on Reddit I think explains why I think there is a big difference between C and C++ and why in my opinion Rust is not the best substitute for the former:
I agree with the view of "portable assembly", or to say it more correctly, language that allows high level of control. Rust at least aims at that, so it should be a good replacement for C.
Some things were still missing though, if I remember correctly something like handling memory allocation errors was an issue, which is important for embedded systems and similar scenarios. I suppose there was some plan to address that.
https://old.reddit.com/r/programming/comments/d50u9g/why_go_...