First of all, Epic already said that there is going to be another language. It’s just the question of which one. They don’t want to make such a decision lightly. So, the argument of the bug issues introduced by the bindings is out of the way. You will have them with any language.
Obviously my personal choice would be Rust. Rust is a good middle ground between safe and fast. Virtually this: Rust = C/C++ + C# + F#
Secondly, Rust is native, so regarding interface speed it certainly beats any managed code or interpreted language like C#/F#/Python/Lua, etc. Obviously regarding run time speed it’s faster than them, too.
The only issue I see is that Rust needs to be learned. C# for instance, a ton of people already know it, especially Unity devs to whom Epic may want to appeal with UE5. And to make things worse, Rust is indeed a notch harder to use than C#, it’s still a native code/system language and not the typical managed code. You have to handle the pointers, because although in safe code Rust there won’t be issues during run time, there will be issues during compile time. Yes, Rust is very famous for its very user friendly compiler that is quite informative with is suggestions to fix its errors and warnings. New comers like me would know…
I’m afraid that there is zero doubt that C# is the community favorite. And because of that eventually will make it into UE5, and not Rust.