HTML5 is not going to replace native for things over time simply because it's not the default way to do things on mobile platforms. The best chance of HTML/JS everywhere was webOS, now FirefoxOS. Everything else thus far has been a hack, even if a very pragmatic one.
HTML5 for iOS/Android is like Flash or Java applets are/were for the web.
I'm not sure why web geeks hate Flash or Java applets so much and are trying to do the same thing for mobile apps.