I remember when the USAF got rid of the F-4 because its airframe was over 30 years old. Hey, MY airframe was over 30 years old!!
But we can't save every single airframe as a memorial. I hope that we do save some to populate some museums though.
About a million years ago, I was at the Air and Space Museum. One of the Docents was giving a nice talk about one of the transport aircraft. I forget which one. It was one of the smaller not so famous ones. He made the comment about flying on one as a crew member in the Korea timeframe. One of the visitors asked him if he flew on this type of aircraft.
He responded that he flew on THIS aircraft.
I wished I could have corralled him and asked him a ton of questions. I think he would have known the answer.
Imagine being a Docent in a museum with your aircraft in it.