A big difference is that Rust has a zero overhead interop with C, so it it allows mixed projects or gradual porting. So Scala or Kotlin replacing Java, or F# r

A big difference is that Rust has a zero overhead interop with C, so it it allows mixed projects or gradual porting. So Scala or Kotlin replacing Java, or F# replacing C# may be a better analogy. What happens there, is that Java and C# are improving just enough that many people are simply not considering the change... And C++ are trying really hard nowadays too - new version with interesting features every few years etc... (By the way - I'm a Rust fan, and also a functional programming fan, so I would be happy if C++, C#, Java would slow down a little to let the alternatives really catch up popularity;)