Yeah and you've underestimated how much mobile web apps will dominate. There will always be native apps, but their percentage of total mobile apps will dwindle. Many, many apps require nothing more than what webkit offers today. A couple years or less of hardware performance increases will push us past the inflection point.

But the main driver will be supply. There just are'nt enough Android, iOS developers. Web devs are legion.

And no cross-device solution will be able to keep pace with webkit & HTML/CSS.