Rust is not a good replacement for C++, though. It doesn't even have inheritance, let alone multiple inheritance and/or multiple dispatch.

It's kind of in-between C and C++ in terms of capabilities, and neither a subset nor a superset of Ada's features in terms of safety. Some of Rust's memory safety features are only now being added to Ada and not yet in the forthcoming standard, whereas Ada has many features that Rust still lacks (e.g. integer range subtypes, OOP with inheritance). Rust is less secure than Ada/Spark, though, and clearly not intended for high integrity systems.

It seems that the niche Rust is aiming for is "safe general system's programming for people who primarily use C and C++ but have never used much Ada or Haskell", and in that area it's quite successful.

Both Rust and Go are odd, because they have less features of C++ (plus added safety) and attempt to sell a lack of features as advantages, whereas in reality no one forces you to use a feature and their developers are merely pushing their own, personal agenda about "what's the right thing to do". I personally don't like C++, but one of its benefits is that it leave its users the choice of what's the right thing to do and offer as many zero-cost abstractions as possible. Rust and Go are way more patronizing.