You're right. The worst case scenario I see is people with zero or negative equity in their homes will become prisoners of their homes. Of course this will reduce a family's mobility and cause greater employment risks, but I think we are dealing with a small portion of the population in this situation.When that phony economy crashed all people had to show for it was worthless pieces of paper, not real estate.
Plus, just because you owe more than your house is worth doesn't mean you can't sell it for less. It just takes some additional wheeling and dealing. Those who are in college right now might consider a career in the loss mitigation dept of a bank. There will be serious demand for that expertise IF the market flattens or declines.