The problem with Rust is that it's not compatible with C++ other than at a C FFI level. Rust code can't really interact with C++ code that uses templates, which

The problem with Rust is that it's not compatible with C++ other than at a C FFI level. Rust code can't really interact with C++ code that uses templates, which is pretty much all of it. That makes it a non-starter for companies that have millions of lines of C++. Incidentally this is why there's basically no Rust in the Google monorepo. Rust might be slightly better than C++, but it's not a lot better, and bifurcating the entire ecosystem for something that is marginally better isn't worth it.