It's simple. Once the computer is as safe as a human driver it will be implemented. Then laws will be altered to cater to the new technology and then the computer will be safer than the human driver. Over lapping technology is being rolled out. Mandates on personal vehicles ( 4 wheels ) are coming into law. Autonomous braking and lane change assistance. It will all roll out very quickly, ten years at most is a very realistic estimate.
No different than the horse and buggy. Things become antiquated. It's only a matter of time. How long did it take for people to latch onto radio ? TV ? telephone ? cell phone ? computer ? smart phone ? And you can still use the older technology if you want. It still exists in all these examples. But is it the most efficient and profitable ? In a business setting ? Are there companies out there still moving stuff with beasts of burden ? Of course. Dude down in West Virginia has a team of mules to put your trailer up on the side of that damn mountain you chose to live on. I'm sure he makes a good living. But is that anyway to move freight from Phoenix to Phili ?