"It's already a problem. In fact, it is the problem. The web application 'platform' is poor, incoherent, and its proponents highly resistant to the sweeping changes that would be necessary to compete with a native, proprietary platform like iOS."
Which "sweeping changes" are those?
Changes like the ability to draw pixel-by-pixel? Vectors? 3D? (Canvas/svg/webgl)
Changes like higher level form controls? Got some in HTML5. New component model is under discussion now. Better layout of controls? The flexible box model helps a great deal, is already in lots of shipping browsers and is getting further cleaned up now.
Drag and drop? Yep.
How about the automatic data binding that's so cool in Cocoa? Not only are there application frameworks that do this (SproutCore, Knockout, Batman), there are also proposals like "Model Driven Views" (MDV) which use ECMAScript Harmony Proxy objects to make it cleaner.
What about files? Yeah, there are file APIs. Databases? localStorage is a simple key/value store. There's also WebSQL DB and IndexedDB which will hopefully be resolved in one way or another soon.
APIs for audio and geolocation are there now. Camera and other device APIs are in the works.
So, which sweeping changes do you mean? The ability to compile C code? Sorry, but I don't think most apps need that.
"The browser makers (especially Mozilla) seem insistent on leaving us in the lurch, stuck with JavaScript, the DOM, and the painfully long lead times of standardization."
I can't say this for sure, but I'd be willing to bet that:
a. standardization is moving faster than it has in more than a decade
b. many APIs become usable in the real world well before the standards are complete
To be sure, the web-as-a-platform is not perfect today or in the future. But, its evolution is real.