Yeah, I've always wondered this too. It would be cool to be able to extract typings in a separate file, like source maps, and send over the wire along with the JavaScript bundle (for compatibility).

It would definitely help moving sections of the code up the tier ladder, not unlike Web Assembly.

I even predict that future typescript versions would include stricter typings optimized for an browser to solve problems like others have mentioned in the thread.

Or just a TypeScript engine in the browser, like ehm Dartium. I guess someone at Microsoft already did this on IE in a hackathon or something.