From cnn.com: Welcome to the 4% return market - The Term Sheet: Fortune's deals blogTerm Sheet
"4% is not horrible. After the two big stock drops of the 2000s, the market basically went nowhere for the following decade. In a 4% market, with compounded returns, the money you put in the market now will be worth nearly 50% more in a decade.
So while it might not be time to be scared of the market -- the economy is improving -- it's certainly a time to be less excited about it."
This is a more sobering prediction than most. The comparison to the 1930s era is not an apples-to-apples comparison. I would think this is the lowest bound. The reasonable average range can be 4-8%; definitely not 10% (also see the associated comments).
More importantly, this is a time to consider putting some fund into the stock market depending on one's time horizon and risk tolerance; for the next 4-5 years of low-interest-rate environment. As they say, "Don't fight (i.e., bet against) the Fed."
Just my input without retribution:-)