This is impressive and cool, but I think web-based gaming will never catch on with the 'hardcore' for a few reasons.

For one, C++ and the native toolchain is still more efficient. But it mostly comes down to perception and convenience. The perception of web-based games is that they're casual and cheap. And most hardcore gamers like to have a copy of the game on their computer - they paid for it, they want a copy that they can keep (and at least store on their hard drive) for years. They don't want to stop playing a game because the dev decided to end its life...

This is why platforms like Steam, Xbox, HumbleBundle, etc..., still rule for distributing games (both AAA and indie).