Wait, what? How is that related to autonomous vehicles? Ok, let me back up a bit...
This question specifically asks for the least obvious ways autonomous vehicles will change the world in the next two decades. Given that, let's establish what progress autonomous vehicles will have made in that timescale, and also start with a list of obvious things to get out of the way.
Current middle-ground estimates for when legally approved autonomous vehicles will be able to operate on public roads range from "next year" to 2025. From a technology standpoint I agree, but I'm not confident the bureaucracy will follow suit so quickly - perhaps in a few places, but certainly not everywhere. (Even as I write this, Google's self-driving car division is pushing the US government to make changes to federal laws that are expected to take decades to implement .) But within five to ten years of the first cities having the benefits that autonomous vehicles bring, there'll be sufficient public and industry pressure to force the laggards into line. When the benefits are so obvious, and the safety record puts humans to shame, you'd be a very short-lived politician if you tried to buck public opinion and insist on banning them.
We're already seeing every major vehicle manufacturer [2-5] putting massive resources into the technology, and even 3rd parties like NVIDIA building technologies  specifically to support this industry. It's a safe bet that within that same sort of timeline (5-15 years) the technology behind vehicular autonomy will have become commoditised enough that every brand will have at least a few autonomous models or options. Within the two decades allowed by this question, I'm confident not only that autonomous vehicles will be commonplace, but that most societies will also have changed their laws to allow unmanned vehicles (i.e. empty vehicles, or passengers only - no human driver/supervisor) to operate on public roads.
That covers my expectations of how far the technology and social acceptance will change, so given that, what are some obvious ways the world will change?
- People who currently cannot drive will have a new sense of freedom. This includes the blind, people with other disabilities, many elderly citizens, and children. This will massively alter the total addressable market for many businesses, and likewise the available worker pool for many others.
- Growth in domestic air travel will slow, as families take holidays where travel is done while sleeping in their vehicles. In an eight-hour sleep, you can quite easily travel 800km (500mi) - enough to get you between many cities in Europe and the US.
- Electric vehicles will dominate the new vehicle market, and autonomous vehicles will automatically dock with with their chargers too. It's certainly possible to build an autonomous vehicle around an internal combustion engine (ICE) vehicle (I've helped do it! ), but by the end of the two decade window there'll be so many good reasons to go electric that ICE vehicles will come to seem like an anachronism.
- The transport industry will be heavily disrupted. Taxis, ride-sharing, and potentially even many forms of mass transport will disappear, replaced by the ability to quickly call an auto-cab that you don't need to share with anyone else.
- Traffic accidents, vehicle related injuries, and even air pollution levels will all fall dramatically. The world will be a safer place to be a pedestrian, and with fewer humans accelerating and braking over and over again, it'll be a healthier place too. Fewer traffic jams too, since the majority are caused by human error, leading to far more consistency on commute times and thus a shorter duration of peak "hour". The other main cause of traffic jams is simply that everyone wants to get to work at the same time (hence, peak hour) but with inter-vehicle communication and better reflexes, autonomous vehicles can be more densely packed on existing roads; effectively increasing their capacity.
- There'll be fewer vehicles overall. As many people have noted, there's far less point to owning a vehicle that sits idle most of the time, when you can rent one just when and where you need it. For people who do keep a permanent private vehicle, leasing arrangements will be more popular, as the rapid improvements in capabilities will see society transition to the 2-3 year upgrade cycle seen in mobile phones today. This will necessitate changes to the taxation model that pays for roads, since in most countries it's currently part of vehicle registration costs.
- We probably won't need to build any more roads - ever. As I said above, better reflexes and communications mean autonomous vehicles can increase the capacity of existing roads. If people can sleep, get dressed, shower, or perform other time-consuming but necessary tasks in their vehicles, we could expect to see a shift in "core hours" for many workplaces. This would then shift or disrupt the concept of peak hour, meaning the capacities for which road networks are currently designed are excessive in an autonomous-vehicle powered world. Yes, population growth still exists (well, not so highly in developed countries any more) but I would be surprised if growth in demand wasn't outpaced by reductions in the peak usage required.
Here are some not-so-obvious, but very likely ways that autonomous vehicles will change the world - and remember - within the next two decades.
- You'll start to see more motorbikes on the roads. If you've never tried it, start this train of thought by accepting my assertion that riding a motorbike through traffic is amongst the most fun - and yet still legal - things a person can do in this world. It's visceral, deceptively fast, and feels like you're playing cat-and-mouse with the rest of the vehicles on the roads. It's also dangerous. Humans are absolutely terrible drivers, such that the top three killers of motorcyclists are inexperience, alcohol, and other people's cars through no fault of the rider. As the proportion of homicidal maniacs in heavy metal killing machines decreases, replaced instead by rational rule-following computer systems, the pleasure of zipping along on a motorbike will only increase as the risk to life and limb of doing so falls. I have every expectation that a great many car enthusiasts will make the transition to bikes as their insurance costs for manually driving a high-powered vehicle rise through the roof. (On the same note, and for similar safety reasons, we should also see an increase in cyclists; fear of the dangers posed by vehicles is a commonly cited reason for why commuters don't cycle instead [8,9].)
- The cost of autonomous electric vehicles will be partially subsidised by electricity companies who will use them as a battery bank for demand-response infrastructure. A Tesla Model S carries 85kWh of energy when fully charged. By comparison, their home battery solution (the Powerwall) holds 7kWh. That means all those parked or idle cars provide a far greater source of on-demand energy than home batteries do, and the power companies are already excited enough about home batteries and connected device demand-response infrastructure . (These provide the ability for the power company to buy-back people's stored power, or automatically turn down their air-conditioners to reduce load, far more cheaply than they can generate more power by spinning up additional power stations.)
- In the long-run, autonomous cars will be cheaper, not more expensive. Many of the expensive bits of current era vehicles are there to protect us from ourselves. If we stop driving them ourselves, much of that safety equipment becomes less relevant. In addition, although electric vehicles are expensive now, in general they're considerably simpler than ICE vehicles. As I've said above, for a variety of reasons autonomous vehicles are incredibly likely to jump onboard the electric bandwagon, and will thus benefit from the reduced costs due to mass production of batteries, electric motors, and the like. Yes, there are costs of sensors and computing power, but again mass production will drive these down significantly - LIDAR sensors have already seen a ten-fold reduction in the last five years, and I'm confident of another ten-fold in the next decade . And finally, through a combination of subsidies by power companies, ad-supported vehicle rental, reduced need personal ownership, and more, the total proportion of household income spent on transport will fall significantly - and that is a huge change in and of itself.
- Sales of board games will go gangbusters. We're here at last! You've stuck with this answer as I've explored the numerous changes that autonomous vehicles will bring to society; lower pollution, faster and more reliable commutes, less vehicle-related injuries, increased personal freedom, lower household expenditure on transport, more usable personal time, less national budget spent on new roads, and more domestic travel done by car. One fairly non-obvious ramification of all this is that autonomous vehicles will lead to a renewed focus on family. Vehicles will be redesigned around the family circle - literally - by reversing the front seats and sticking a table in the middle. And if families are looking at each other, then road travel becomes an opportunity for togetherness, bonding, and play. Instead of the backseat evolving into a small cinema, families can actually do things together, instead of turning to isolated experiences because they can't communicate properly. Given that opportunity, what better to fill the table than one of the fastest growing gaming segments in the world  - board games! (All this said, I can just as easily imagine a slide-up double sided television emerging from the center of the table to perfectly isolate the adults from the kids. Such is human nature, I guess...)
The world will change significantly in the next two decades, and autonomous vehicles will most certainly be one of the most impactful forces. While much of their impact is obvious and inevitable, the cascade of changes they bring about lead to an exciting concert of possibilities. I've presented some of those I feel are both non-obvious, yet also likely. I can't wait to build the future and prove myself right!
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(Originally answered on Quora at: http://qr.ae/ROxTTi)