I doubt those languages would have the same level of traction as Rust, especially now that Rust has already gotten said traction over the past decade with even the Linux kernel using them. It's more likely that Rust will be written as today and then these extra features are added for more type safety in certain functions as like I said in another comment I doubt people are going to write type contracts for every single function (maybe LLMs will, but that's an orthogonal discussion).
Apparently you missed Swift.
Linux kernel adoption of Rust hasn't been a smooth ride, exactly because of its type system among C folks.
It is only happening because the likes of Google and Microsoft want to see it through.
Swift is not really for systems level programming like Rust and interestingly some projects like Ladybird have moved away from Swift towards Rust.
> Swift is not really for systems level programming
Apple seems to think differently.
> and interestingly some projects like Ladybird have moved away from Swift towards Rust.
Not really interesting after you spent some time tracking lifecycle of FOSS projects. I don't think it is a last "moving away" announcement we get from Ladybird.
It certainly is for Apple, regardless of your opinion.
It is all over the place in Swift documentation, WWDC sessions, and even last week on Meet the Team session, regarding on how to write safe systems programming code on Apple platforms.
Ladybird should focus on what language they actually want to deliver something.