This is pretty simple. The Dression of 2009 will start because people act in there own best interests based on the trends that they see.  So far since the crisis started they have seen that:

• The government stepped in and “saved” the banks.
• The government stepped and “saved” the insurance companies.
• The government stepped and saved investment firms.
• The government is stepping in to save the US auto makers.
• The government says it will save the homes of people who are three months behind on their mortgages.

People who pay rent will see this trend line, rumors will fly and many of them will stop paying their rent in expectation that the trend shown above will continue.  Then the Depression of 2009 will start.  Actions have consequences.