I would guess that the average person might cover .5 mile (< 1km) in 10 minutes so it wouldn't be possible to reach the parking that's located "many miles" away. Also, I didn't say your car is 10 minutes by foot away, more like 10 miles. It could easily be 15-20 minutes for your car. Your goal is to minimize your commute time not your cars.
This wouldn't work in NYC or London, which are much bigger cities than discussed in the article. The first leg of your journey there should be a train whisking you away from the city at 120 mph to a train station within 15-20 miles of your home where your car will leave home to pick you as soon as your phone tells it you are 15 minutes from your station.
Same number of cars as today. Granted, each car will be driving a little more but pickup and dropoffs could be made more efficient with taxi stand pull-up lanes, for example.
I think the commuting option doesn't seem to work for many people. Seems like people spend too much time on the lawn, but sure it does work for some people.
This wouldn't work in NYC or London, which are much bigger cities than discussed in the article. The first leg of your journey there should be a train whisking you away from the city at 120 mph to a train station within 15-20 miles of your home where your car will leave home to pick you as soon as your phone tells it you are 15 minutes from your station.