The median age of a new car buyer is 53. It has always been the wealthier folks purchasing new vehicles.
Fortunately there are a lot of Boomers still around, buying cars.
While this isn't exactly what age demographics should look like (should be more pyramid shaped), it's not too bad compared to many other countries.
We're going to have new car buyers.
Median income has held on.
... I expect autonomous taxi service to be well below the cost of private vehicle ownership in about 15 years. Considering paying the driver is 75% of the Uber fee, that $20 lift to the airport becomes $5. You can't even park for a day at the airport for $5.
Very quick back-of-the-napkin estimates;
$5 ride to work and $5 ride back home 5 days per week = $2,600 / year. Even if it's twice that cost, how many people are spending less than $5,000 per year on car payments, fuel, maintenance, insurance, registration, car washes...? Public transportation is in it's last years, as nobody is going to ride the bus when a personal ride is $5.