As you know, I've been doing my own extrapolations recently, based on the Dow since 1928, and the implication is that the low point could be as deep as c. 4,000 points, i.e. another 50% off where it stands today.
Now, "Mish" looks at revised earnings estimates for companies and relates them to stock prices, applying various price-earnings ratios. His conclusion is broadly the same.
As Michael Panzer predicted* (reviewed here in May 2007) there's been a flight to cash, and now (as he also predicted) it looks as though inflation is set to roar. This will disguise what's happening to stocks, but underneath it I see that decline. As in the '60s-'80s. it may take some years after the apparent turnaround before real values increase again.
Provided you trust the government to pay up when due, and to calculate inflation fairly, National Savings Index-Linked Savings Certificates (or US TIPS) may be a valuable weapon in your anti-inflation armoury.
*"He predicts first a credit squeeze, which makes cash king and ruins our credit-dependent lives and businesses wholesale; then hyperinflation, as the government prints money to keep the system from complete collapse.
In this scenario, at first, stocks, corporate bonds, property, commodities (including gold), even government bonds and savings certificates, all decline in value against hard cash as everybody scrambles to settle their own debt, collect what's owed to them and continue to pay the bills. Then the hyperinflation hits and everybody tries to offload their currency."