I find this not necessarily true at my company, in fact the oldest people in the engineering department are exclusively developers where the managers tend to be younger or the same age as them. This may depend on region, as well, the area I live in now is rather different than Silicon Valley where I think people wouldn't stick around for years and years as "just a programmer" but in lower-cost, slower-pace areas, I think programming is often just another job to people and its something that people will just continue to do for their entire career.