At Nvidia's GTC conference in California, Tesla's Elon Musk has given us yet another glimpse into his view of the future. Talking to Nvidia's CEO Jen-Hsun Huang, Musk said that, in the future, driving cars might be outlawed. "[It's too] dangerous," he said. "You can't have a person driving a two-ton death machine."

Huang and Musk were on stage during the GTC 2015 keynote, ostensibly chatting about the computational challenges of computer vision and deep learning. Then, Huang decided to ask Musk, in fairly general terms, how the whole self-driving car thing will actually go down in practice. "I don't think we have to worry about autonomous cars, because that's sort of like a narrow form of AI," Musk replied. "It's not something that I think is very difficult, actually, to do autonomous driving, to a degree that's much safer than a person, is much easier than people think."

The difficulty arises, though, when we have a mix of normal and autonomous cars on the road. That's where Musk's "you can't have a person driving a two-ton death machine" line comes into play. When every car is autonomous—and optionally also talking to each other via a car-to-car mesh network—you can cram a lot more traffic on the roads. Throw a dumb human driver into the mix, though, and suddenly you have to go back to the old way of doing things, with enough space between cars that humans actually stand a chance of braking or maneuvering in time.

This is one of the thornier issues facing self-driving cars. As of 2010, there were around 1 billion motor vehicles on the road—all of them driven by humans. It will take a long, long time until a significant fraction of cars are capable of autonomous driving—and longer still until the world's roadways are entirely populated by self-driving vehicles. On stage at GTC, Musk noted that car and truck production is limited to around 100 million vehicles per year—so there really is no quick way around it. In the mean time, we will most likely see a lot of cars that have increasingly smart and autonomous features—lane keep assist, adaptive cruise control, car-to-car mesh networks that allow for faster braking and denser traffic—but without being fully self-driving.

The full conversation between Musk and Huang at GTC 2015 is available on Ustream, starting at around the 1 hour 37 minute mark.