...the median age of automobiles in the US was 9.7 years. [Seems high].
Don't forget many of those used cars that people get rid of to buy new cars end up being owned by people without the money to buy newer cars, become cars for students, etc.
Us: the car that is nominally mine is a 2009 with 50,000 miles, the car that is nominally my wife's is a 2004 with 118,000 miles last I looked. In a couple of years they will be 5 years old with ~80K and 10 years old with ~140K. Around then we will begin to think about replacing the older one depending on how it is doing. We typically keep cars until 12 years old, but could go a year or two on either side of that.
We live a world with knowledge of the future markets has less than one significant figure. And people will still and always demand answers to three significant digits.