There is a reason why we're using the World Wide Web right now. Its not an app. Its an ecosystem based on standards where everyone agrees more or less to play by the same rules. Its also easy to learn so anyone can put anything online, it doesn't matter if you're building a home page about crappy gingerbread people, you don't need permission from Apple or Google or a lot of knowledge to do it. The Web won as main medium to exchange stuff because its easy and open.
Initiatives such as NaCL and similar are not open. ASM.js based stuff work even on platforms that doesn't support it. Its about being compatible and playing well with others.
Mozilla is a strong player and it is not playing a game where the others need to lose for it to win. Its playing a game where cooperation is the main objective. Firefox OS doesn't need to win, it just need to show people that you can do whatever you need using web technologies that don't belong in a silo.
Sorry if this sounds like a rant but I get really frustrated when people seem to be content to throw all the advancements we did for the web during the last 20 years into something as shallow as user base numbers.
Four years ago no one could believe that a whole OS could be built on top of a web engine. That browser would be able to play AAA games without plugins. That we could do videoconferences using p2p with nothing but HTML/CSS/JS and yet we can. Now, put your imagination and dreams to work and imagine what the next four years will bring. Thing a bit longer and imagine what could happen if instead of trying to embrace proprietary tech we decided to move the web forward...