That'll likely be true - but not because short men have died out, but because the average keeps increasing. I reached 5'9" the summer I turned 15. Was happy about it, as it meant I was "average" finally, and had three more years of growing left. Stayed 5'9" until I was 22, when I grew an inch. Was happy about that until the new census came out, and the average was 5'10"... then I grew up and stopped giving a shit about it.