I think one of the things holding back some of the more impactful features we could see in C# is the need to also update the CLR in many cases to handle things like new kinds of types, new kinds of expressions, etc. TypeScript has the benefit of being executed by a dynamic runtime, but C#'s runtime is unfortunately statically typed, meaning it also needs to be updated with the language. It's also used by multiple languages, for what it's worth.

That being said, if they redirected some of their efforts towards improving the CLR as well, I think they could put out all the cool features they've mostly sidelined, like DUs and some form of their extension everything proposal.