There is absolutely no slightest hint of "throw it over the wall" in ISO C++ development. The compiler implementers and heaviest users work deeply and collaboratively together to bring each Standard to readiness. Each new C++ Standard is a markedly better language than any before. A mature language, C++ necessarily evolves more slowly than Rust does, but Rust will soon become more stable, too, ISO or no.
What does it mean when you feel a need to lie about your perceived competition?
In fact, there is no such competition: literally hundreds pick up coding C++ professionally for each individual who so much as tries out Rust. The fast rise of Rust has no detectable effect on the growth of C++ usage, even 40 years on. Rust's and C++'s coexistence will last for as long as Rust is used at all.
You are welcome not to like C++, but lying about it says more about you than about it.
The fate of Gcc-Rs will be determined by future events unknown to you or to anyone else. It could become critically important to Rust's own future, someday.