Market returns are based on the amount investors need to take the inherent risks. Unless stock market investing gets considerably less risky (seems quite unlikely) investors will leave the market for less risky vehicles until rates return to the amounts needed to justify taking the risk, which have historically been around 7-10%.
Stocks, real estate, bonds, and all other market-based investment vehicles will always have returns in-line with risks in the long run.
Nobody should ever retire hoping to get a steady income from the stock market or real estate or other volatile investments. By the time you're ready to retire, you should be entirely in FDIC-insured CDs and the like. If your retirement plan is contingent on 6% annually you're asking for trouble, and you're probably going to get it if you live long enough.