Test are being performed today using vehicles that could already be put on the road and sold to people but there are, naturally, obstacles that must be overcome first. Then no telling what the cost would be. I fully believe though that we will soon see self driving vehicles on the road and sold to the American public but I also think another evolving technology will start to become visible in the coming years and that is vehicles that travel the road and yet with little effort transform into a small flying machine.
It's kind of ironic to think that just about the time that people start producing vehicles that drive themselves along our roads that cars that fly will start appearing and create a whole new set of problems. Not only are legislators going to have to come up with a whole new set of rules and regulations for cars and vehicles that drive themselves and robotic type vehicles but for the potential that our skies will become the new highways of the future. Rules and laws will have to be thought out for that new reality because you're not going to want to have vehicles colliding into each other above our heads and dropping out of the sky whenever someone makes a mistake.