One of the benefits that web development offers that the App Store doesn't is that the code you write runs on any machine that has a web browser. Certainly dealing with IE is a headache - but to completely discount that fact that it doesn't run on Windows and ignore the majority of potential paying customers seems silly to me.

Certainly people can and will make money selling software in the App Store - there are some good reasons why listed in the article - but I disagree that web developers being acquainted with Mac OS tools is going "to put a final nail in the web-coffin". Web development seems alive and well. It is not dying - it is still in it's awkward adolescent years.