Why does the OP compare the web to the iPad? The iPad is really just another standalone computer running a native OS like the Mac or the PC. In this context, he's really just comparing web applications to desktop applications, which is a comparison that has been made for years. Nothing new here.
Locally installed applications are slicker and more responsive than web applications. They always have been, yet developers have moved to the web in droves despite that. Why? Because the web offers other advantages, like being accessible from anywhere, for one. It's the closest thing we have so far to the dream of write once, run anywhere.
"People use web search today because they don't know how else to find high quality information."
That's what search is. No point in searching for something if you already know where it is.
"The web is a mess of content with no organization. On an iPhone, I launch the appropriate app"
Great idea, if you can organize every bit of info on the net into its own app. I wonder how many screens that would be on an iPhone?
I agree that browsers are constrained in how they can innovate, and it is a problem. But the web is not going away. Search is not going away. And iPads are never, ever going to replace the web.