I'm glad to see other options like Dart and PNaCl coming along. It's about time.
and many others, for example me
However the adoption of a new VM, I think, will be challenging. It will be telling if Mozilla will develop one if this actually goes through standardization. My instinct tells me they won't and that Dart will continue on as another "transpilation," language.
Eiffel, scarcely used; C#, used only for some Windows development.
(I know I am misrepresenting each of these languages slightly, C# in particular as I'm ignoring Mono.)