2% is real. The US has average around 3% for years now. And since I don't believe in the tendency of the rate of profit to fall I don't think assuming at least 2% is unreasonable. But let's say zero. Does anyone really think we'll lose the ability to care for the old?

Here's the simple way to think about pensions/SS: we take about 4% of GDP and cut checks to old people. They buy food and pay their rent. Nobody starves. It always works, in 1961, 2011, 2061, whenever. Anybody who says otherwise is trying to fool you.