One way that this could be accomplished is by creating all downtown places for only foot traffic and bikes. By eliminating cars driving through downtown areas, it will reduce the demand for parking lots as well as providing space for more urban planning as discussed above.

I would rather see satellite parking garages (topped by solar panels or gardens as Edward suggests) for people who live out of town, and downtown areas reserved for pedestrian and bicycle use. I have heard a speaker on urban planning state that people will spend more time in a shopping area if their car is somewhat distant, as they visit more shops, enjoy resting on a bench, maybe have a coffee or bite to eat, whereas if they drive up and park in front of the store they plan to visit, they are more likely to dash in, purchase what they came for, and zoom away.

Europe offers bike racks from which you can rent a bike, ride to your destination, and turn it in for the next person. When done with your shopping, browsing, visiting, picnicking, and strolling, another bike is waiting for your return to the parking garage.

We don't need or want cars in town so we don't need any parking lots. I have commented in other places about how to accomplish this. Some of these parking lots could be either public or commercial gardens. Such things, when properly managed, help store carbon in the ground where it belongs.