For decades, my sister prepared photo albums of trips and important events. She has a large stack of them. Now she is disassembling them and sending them to a company to scan them.
The most sentimental of things (of objects) photos, records, "letters and papers" are becoming electronic. One can readily argue that these are physically smaller things, but they are also emotionally large objects. As sentimental objects no longer need a physical presence, the less sentimental items may eventually need less of a physical presence as well.
The young people I know seem to be less sentimental about family heirlooms than my generation or my parents' generation. This current generation seems more ready to put objects they no longer use for sale online.
The average size of new homes built in the US hit a peak in
2015 and is trending smaller. In 2021 the average size was smaller than 2007. Roughly down 10% from the peak.
This isn't the current generation buying. The average size of rental apartments has been on a
downward trend for 10 years.
My parents bought furnishings to fill the house they had. I have too. I have a guest room. So now I have a second bed and a second dresser. A dresser that contains spare sheets for that second bed.
As living spaces trend smaller, the desire to purchase stuff to fill and decorate those spaces will decrease with the space provided.
The trend is there. But lets not get too far ahead of ourselves. 50 years is two more generations. It won't be Star Trek sparseness but maybe that generation will be less a generation of hoarders than the last couple of generations have been.