Fair enough. I just haven't heard of the ECMAScript standards committee seriously considering adding static type checking to the language. The closest things I've seen are the proposed guards [1] and trademarks [2] features for ES7.
That's not entirely true. While TypeScript is closely aligning itself with the proposed ES6 syntax for classes and modules, there is no expectation that ECMAScript will add optional static type checking. If you want statically typed JavaScript you are always going to need something like TypeScript.
With that said, as ES6 evolves and becomes more widely supported there will be aspects of the TypeScript compiler that will no longer be needed (e.g. classes, modules, fat arrow functions, etc.).
Here's the pitch:
"Rhodes is the industry's first open source framework for rapidly building mobile applications for all major smartphone operating systems. Rhodes allows developers to write a smartphone application once using simple HTML and it automatically builds native applications for all smartphones including iPhone, BlackBerry, Windows Mobile, Symbian and now Android."
[1]: https://github.com/clausreinke/typescript-tools