Go and Rust had the very same self-positioning as C++ replacement, but because of different visions of what C++ is for they are now in largely unrelated niches. It is hard to imagine, for example, that someone would choose Go to rewrite Webkit, or LLVM, or any C++ math/modelling library (for other reason than proving it's possible). Just as an idea of writing website business logic in Rust would make me scratch my head.