senoralligator

Better ways to describe polymorphism, a better type system in general really. Look to async Rust for a great example of such interoperability.

I'll admit I don't use JavaScript very often, but surely the state of polymorphism could be improved? For example, C++ recently added concepts, and most (modern) languages have some way to describe interfaces.

As to your counterexample, I agree with current JavaScript that would be a problem, but with good language support it would certainly be possible. For example, Rust (and C++?) have competing implementations of the global allocator, and must users will never notice.

Surely it would be better to fix the interoperability issues of the language? "Lets just add a single implementation of everything to the standard!" seems like quite a strange response to "users of the language are having trouble with interoperability due to false coupling."