At this point I feel JS won't have to evolve much unless some useful feature needs JS itself to be extended but let AltJS take care of usability and just concentrate on rock solidness, performance and portability between runtimes and developers can just use whatever shiny new version they want to use that runs on old but battled tested runtime without waiting for the whole internet to upgrade.
That isn't going to happen with Typescript. Aside from the type system, Typescript won't be implementing new features until they are in the ECMAScript standard.
