For one example of how the traditional automobile could become obsolete in the not-too-distant future, look at the self-driving car that Google developed last year. It was able to drive thousands of miles on the streets and highways of California with minimal human intervention. It's not yet ready to take away the human controls entirely, or to be released to the public...but GM and Honda have both targeted 2017 as a release date for self-driving cars. Even if they're a few years off, it's definitely coming in the near future.
How will this change society? It will eliminate the need for personal automobile ownership for the vast majority of people. The main reason that people choose to own cars instead of taking public transit is because of the convenience of door-to-door transportation. You get in the car at your house and go exactly where you need to go, whereas you can't do that with a city bus or a train or a metro. Once cars are able to drive themselves, you'll be able to get that kind of convenience WITHOUT owning a car. You could just summon the nearest car with a smartphone app, and it would come pick you up. This would allow for much more efficient transportation, since our personal cars tend to sit unused for over 90% of the day.
Fewer cars would greatly improve environmental efficiency. Aside from the expected upgrades in hydrogen/electric cars and batteries, fewer cars would mean that less real estate would need to be used as parking lots or highways, and could be left to nature (or used to develop cities more efficiently, thereby reducing sprawl). Additionally, cars will soon be able to communicate with one another and warn each other of traffic jams, thereby reducing traffic congestion, which is a major source of environmental inefficiency. Combine this with the self-driving aspect, and cars would be able to arrange themselves in highway traffic patterns that minimize the amount of energy needed to produce themselves forward, much like racecar drivers do.
This is just one vision for how emerging transportation technologies will soon be able to dramatically improve our environment and our lives. I'm sure there are plenty of other innovations that people haven't even thought of yet.