Since the Chrome OS announcement the other day I've been thinking more about what a world with rich enough web APIs to support all general purpose applications might look like. I'm not sure that it'll happen, but it sounds like Google is putting their weight behind it and they've been successful in the past at moving our industry in new directions (remember the world before GMail and Google Maps?).
A richer set of standard web APIs might form the basis for a cross-manufacturer mobile platform. The Palm WebOS stack already kind of looks like Chrome OS (though with local HTML+JS apps rather than remote ones) and the original iPhone application model was exactly what Chrome OS proposes. The limitations that forced Apple to create a native developer platform are exactly the ones that Chrome OS plans to address.
Of course Google's own mobile platform is decidedly non-web and Apple's much larger volume of applications discourage it from supporting standard APIs. The handset manufacturers, OS developers and carriers are all making a ton of money selling applications in a model that's reminiscent of pre-web software models. The only real winners from a move to a web model for mobile applications would be the users.