He is talking about the second law of thermodynamics in realised designs. You can use designs from the 60s today and the result will be a brand new system that

He is talking about the second law of thermodynamics in realised designs. You can use designs from the 60s today and the result will be a brand new system that in time will rot away and need to be replaced by, possibly the same design. That doesn't invalidate what he is talking about. Even the pyramids of Giza will eventually rot away given time. The difference in software, in my opinion, is speed in which change occurs.