Unlike the most recent financial crash that started with the real estate market and nearly took down the global financial system, I see localized crashes or at least, market doldrums, but I think the problems will mostly be local. It may be a case where the outrageously priced areas get the flu, maybe pneumonia, and most of the rest of the country will get the sniffles for a few days.
In this area, and I'm sure in a lot of other areas, prices are so cheap (compared to the coasts and a few other 'big-city' markets) that there's no reason to expect any substantial problems. Our supply is short and there are bidding wars, 12 hour marketing times, etc., but the average price has appreciated only about 10%/year for the past 3 years and our county avg. price is still less than $200K.
I don't see the localized crashes seriously affecting the whole country. I'm sure the "news" casts will play it like its the end of the world since those are the only places that matter to them. I know CA has had some previous crashes and our market didn't even notice. As far as the problems on the coasts, to quote someone, maybe Lou Holtz...."Don't tell people your problems. Most people don't care, and the others are glad you've got them."