I enjoy writing this blog... Please chip in and read the other articles if you so feel. Basically, the jist: Maybe 100 pts of downside. Fascinating to look at earnings and past earnings dips in previous major recessions.
http://scriabinop23.blogspot.com/2008/01/obligatory-armchair-s-valuation.html
http://scriabinop23.blogspot.com/2008/01/obligatory-armchair-s-valuation.html