Since we all tend to live in bubbles to some extent, do we have any numbers to back this up (like, # of repos/commits in each language on GitHub, or questions on StackOverflow)?
I tend to view TypeScript similar to CoffeeScript — it brings to JavaScript some features from other languages that are convenient and preferred by a subset of frontend developers. It allows for experimentation in the language, and helps inform TC39 proposals.
In time, I suspect support will coalesce around a specific TC39 process proposal to add type support, it will graduate to stage 3 or 4, get integrated into browsers and Babel, and enthusiasm around TypeScript will wane.
A flexible type system like that of TypeScript is pretty big and complex. It would take considerable time and effort to get that through TC39, I think. It could happen, but seems far off to me.
I tend to view TypeScript similar to CoffeeScript — it brings to JavaScript some features from other languages that are convenient and preferred by a subset of frontend developers. It allows for experimentation in the language, and helps inform TC39 proposals.
In time, I suspect support will coalesce around a specific TC39 process proposal to add type support, it will graduate to stage 3 or 4, get integrated into browsers and Babel, and enthusiasm around TypeScript will wane.