> after all that shamanic dance trying to get all this to work you will wonder, what's the point.

Shamantic dance? It's trivial to the point of being a non-factor. You wrap your app in Phonegap, and make json requests to the web if you need data from there. Otherwise, it is stored and runs on the client.

> Not many predict that desktop apps will be replaced by web apps soon, but for some reason this a popular view regarding mobile.

For most things, desktop apps were replaced by web apps. Which is why Facebook doesn't maintain a desktop app (or Hacker News for that matter). HTML5 proponents have never made the claim that it will replace all native apps. Instead, it will replace data/list style apps like Facebook or productivity apps, which frankly, make up the vast majority of apps in the app store.