Completely disagree.
I don't even think Google "adopted" NaCl, it's still more a private project of a few, compared to Chrome(OS) and Android.
NaCl is one of those technologies that I secretly hope fails. Pull the plug on x86 already, FFS.
Saying that the Open Web needs an app-store to compete with the walled gardens is also a fallacy. Quite the contrary, the web competes with the walled gardens because it doesn't have such master-record. You will see this pattern repeat itself; the chaotic nature of the web beats any attempts to impose "order" upon it. Cf. the dismal failure of dmoz and other curated directories, compared to search engines.
If you want to use performance critical software that pushes the limits of your machine, download it, use Java or whatever.
I doubt the app-store model will survive long term; individual merchants and vendors tend to move faster than the infrastructure that houses their shops and supports their business (almost literally.) The moment a few merchants diverge from the proscribed machinery of the market, and exploit inefficiencies, as they will, is the moment you will see this model come apart at the seams. If the entire model isn't killed along with its platform by changes in technology.
The one good example I can give you is the buildings built throughout South East Asia to house street-vendors. Specially in Cambodia and Vietnam, the governments built multi-story shopping centers, just piles of concrete, and invited vendors to push their carts in and congregate. The markets might have looked like proper malls at some point, but with time, they're just shaded bazaars like any other street market, except this one isn't dried by the sun and there is no drainage. Over time, the building has all the appeal of a street market, except you have to climb up some slippery stairs tightly packed with pickpockets. However, most higher-end merchants gather around the vertical-bazaars and open proper walk-in shops with more products, better presentation, and all the amenities of a private property (fan, seats, water cooler, bathroom, TV/radio, etc.)