It would probably make taxi medallions worth even less money.
Package delivery subcontractors and couriers might also be out of business if a package delivery can be made on demand - when you are there to meet the car and open the trunk.
If car ownership plummets, and is replaced by on-demand services, businesses making/installing after-market accessories for cars would suffer e.g. stereos, parking sensors, etc.
AAA and other road-side services.
Towing companies would lose much of their business moving illegally parked cars.
