I didn't mean that manually driven cars will become illegal in 5 years. I said that it would take less than 5 years before some legislators try to make it illegal to have a non-autonomous vehicle on main roads. It would take a long time to get hashed out before it could be voted on, and there'd be a phase-out period where people are given "X years" to plan to make the switch, perhaps with government-subsidized vehicle recycling service akin to "cash for clunkers", or certain vehicles could be modified to be made autonomous. It'd probably start in individual states before gatting national attention, and would probably only apply to certain types of roads at first, but it's inevitable that it'll happen eventually.

It probably won't be fully realized for 15-20 years, but I suspect it won't take longer than 5 years before the majority of people realize how much better their lives would be with autonomous vehicles. Hell, you wouldn't even need to own a car anymore since auto taxis would be so much more convenient and efficient than human-driven taxis.

Imagine if that idea catches on and most people just subscribe to the robot taxi service instead of paying to register and insure a car. The computer network keeps the cars spread out evenly so that nobody has to wait more than a minute or so for a car to get them (in urban/city areas), it takes them to their destination's front door, then go to the next closest customer, waiting station, or refueling station without taking breaks. We could free up at least 25% of the ground space currently being used in urban areas for parking. It will be gradual but I think it's perfectly reasonable to expect to see some of this taking place in my lifetime.