I think Rust would eat into C++ more than C#. Microsoft is pushing C# and the tooling fairly hard right now. Performance is pretty good and even though Rust seems like a rising star, it won't reach C# levels of tooling for quite some time. I don't think the population of studios that chose C#'s performance and convenience over C++ but would now choose Rust is all that large. But hey, lets start talking about bindings…
Just curious; what's the tooling gap between Rust and C#, according to you?
I work in C# profesionally, and dabble in Rust, and haven't really found Rust tooling lacking yet -- but maybe that's because I'm only working on small hobby projects.