All of those only intend to reduce file size or improve backwards compatibility; you don't need those, it just makes things faster and work in a wider range of browsers (notably IE 8 and co).
Unlikely. Unless we were to discard support for all old browsers and all new browsers update automatically and support the same features across devices and OS.
Those things aren't needed to get javascript to work properly, most such "hacks" are necessary because of the DOM, proprietary standards and the ridiculous variety of devices web content needs to be displayed on. Even if you had an alternative language, those problems would still remain.
Will there ever be an alternative language that can allow me to just: write, compile, run in browser?