Will housing sales plummet after the $8k credit driving houing prices down with a new round of resets in 2011?

Sales have been aided by a federal tax credit of as much as $8000 for first-time home buyers which is one factor involved in the recent increase in existing home sales. However, with the tax credit ending 11/30/09 and peak resets in Alt-A and Option ARMS looming in 2011 will the housing value and sales spiral down until stabilizing 2012?