Good point. I should have mentioned monetization is not an issue. In other words, if what we aim to build were in an app store it would be free anyway.
Basically I'm asking whether HTML5 will be mature enough both in terms of functionality and browser market share in around 6 months time.
Never mind six months from now - if you're thinking native app, then you've got a particular set of phones in mind. Take a look at the state of the browser on them now.
andrewf is completely right. You should plan for what capabilities exist today on the platforms you're targeting. Taking advantage of upcoming synergy is a lofty goal, but expecting it and making your plans depend on it would be a mistake.
Basically I'm asking whether HTML5 will be mature enough both in terms of functionality and browser market share in around 6 months time.