> C++ will eventually peak and die off but the timeframe is probably measured in decades and I'm sure there'll places where it holds on even then, like Fortran today. I certainly would't recommend it to a programmer starting out today, instead C or Rust would be better places to get an idea of system level programming.

Unlikely. The only candidates for replacement are Rust and D, none of these are anywhere near the adoption of C++.

What C++ can do is get better at being a language and then maybe give tools for developers to phase out outdated constructs or relics from C. It is not going away cause it's the best replacement for C humanity will ever get, at least for the next century.