Tesla already has the technology for it's Autopilot system in place in it's newest Model S vehicles, it merely needs state approval for the usage. Many other manufacturers have already put out technology to have cars park themselves, collision-avoidance systems and even Cadillac's Super Cruise lane tracking systems, which is essentially Cruise Control for your steering wheel. Google's adorable little driverless vehicles have already logged over one million miles and seems to be the closest a potential private transit system.
Andrew Del-Colle, a writer for Popular Mechanics, predicts that once enough cars are able to drive themselves, local governments will begin creating special lanes, like HOV lanes, for these vehicles. You simply drive your vehicle into the lane yourself and initiate the auto mode. This would be great for long road trips across the country. Although you may have plenty of extra time during these auto cruises, it is expected that the driver remain conscious of the activity going on around him, in order to prevent any accidents from occurring.
At some point, auto manufacturers will design these cars to speak to each other. Vehicle to vehicle (V2V) technology will allow the cars to sense what each vehicle is doing and will take it's surroundings into account in order to prevent accidents. Del-Colle also mentions the ability to communicate with our infrastructure, such as stoplights, crosswalks and railroad crossings. This level of communication would revolutionize the way our roads and transport system deliver passengers around cities and states.
If this technology continues to be put into place, it seems inevitable that humanity will approach a fully autonomous state, where the streets are filled with nothing but federally owned 'pods' or 'containers' that we will all use as public transportation. We can request pickups at certain locations, drop off anywhere and have access to in-vehicle entertainment systems. In order for the rich to feel in power and for the general masses to feel more comfortable, the streets will probably allow individually owned 'pods' to access the roads. These pods would more than likely be made by today's large automakers and promote individuality.