This didn't have to be boring dull preservation for Posterity. They could be run backwards so that you can hear hammers un-striking strings that were being detuned. Old rumbling uprights can be pitted against clear new grands. A while later, we got still more ideas. You can hear this now.
Cassettes are available.
However much music-teachers and our culture would deny that. Even those who had and kept pianos would sooner or later come to regard the piano as primarily furniture. The appearance of a grand in some well-appointed home or important studio would be what matters, rather than how it sounded. The actual deterioration and neglect of real pianos would seem of less and less importance when better and better electronic instruments hit the market. It's really too late now.