You can do that now effectively. Many apps today use a base webapp that can be changed at any time and a thin iphone shell over top of it. And change the app

You can do that now effectively. Many apps today use a base webapp that can be changed at any time and a thin iphone shell over top of it. And change the app all the time. And don't get any problems from apple. Also in app purchase would be fairly easy to integrate with a webapp json api and an an iphone app wrapper to handle purchasing.