This article assumes that autonomous vehicles are implicitly community/fleet owned and managed. It is not yet clear to me that this is going to universally be the case, and that I (people in general) will only travel in autonomous cars with an amount of luggage that they are prepared to carry at every stop.
Imagine now, “most days”, you just commute to work and home again, so this is not a problem, but “some days” you want to stop at the shop on the way home from work, or on the way to work to buy a cake for morning tea. Do you want to carry your work briefcase into the shop with you, because you will complete your journey in a different car? “Some days”, you will intend to go somewhere else after work, do you want to carry your golfing clothes or dinner suit to your office because you can’t leave it in the car? Do you want to carry your work clothes to dinner and a show? Maybe I’m just highlighting a new industry of a large locker pool instead of a carpark. Certainly the car parks can be moved a little further from the office/home/theatre, but I think there will still be a demand for personal-use vehicles for a long time after they drive themselves.
I can imagine that the pool of self-driving fleet vehicles might replace the “second car” for a lot of families, but it will be much slower to displace all of the cars in a family for a lot of families.