If you look at current and historical P/E’s 6000 is not a bad guess. If your understand that some of the E’s will further drop because of a lot of debt that will default, 4000 may not be such a bad guess. We have been through a galactic sized global financial bubble.
PE’s are well under the norm now. 6K would be belly up territory. We don’t have a belly-up scenario. We have a liquidity issue in the credit markets. Not a major business disaster.