Lets see... some random thoughts on various points here:
One thing not covered here that I would predict is that if we went down this road, cars will become vastly more expensive... along the lines of 100k-200k in today's money for starter cars. Much of this could be in fees to cover the world wide traffic control system needed, but also because the cars themselves will need to be much more complex and much better tested.
However, this would not directly impact the majority of users since they would simply pay for the part of the time they needed it either in per hour/mile/kilometer fees, or in some kind of car sharing arrangements.
Also how do you get the package from the truck to the doorstep? I don't think car ownership will ever drop below 50%. Only place I thing it will drop a significant amount is in the middle of big cities. And it's already low there.
In most areas the post office is requiring residents to install these combined mail boxes to make their job easier. I could see a time where they were automated and an autonomous vehicle pulled up, dropped off a package in box 123, and texted you that the package is there, the code for the door is "abcd".
I can also easily see it going below 50%... keep in mind that according to the 2010 US census 80.7% of people lived in urban areas. (not saying it would, but not willing to rule it out either)
On Sunday I was getting ready to make a loaf of bread, and realized the butter had expired. I got in my car, drive 10 min to the grocery store in the next town, re-stocked, and headed home.
Consider this:
https://www.amazon.com/b?node=8037720011, far fetched, but certainly possible. Also, with a decent network of autonomous vehicles, you could have one that stopped by the autonomous store and dropped that butter off at your place, probably quicker than if you went and got it. (for most people at least)
Remember where we were 20 years ago in terms of getting things you needed... overnight shipping was reserved for critical packages and cost a TON of money... now in many areas of the country I can get Amazon to deliver things in an hour or less...second day air shipping is commonly free! and 20 years from now, who knows where we will be!
Compare that to the "on-demand" model - I fire up the "bring me a car" app, wait, what, half an hour for a car to arrive, only to find that no one cleaned it out from Sat nights partying. The drunk in the passenger seat threw up on the floor. And I don't even want to know about the random bodily fluids on the back seat.
True, that's a challenge...but I suspect we would end up with tiers of service... there will be the mass transport option that has plastic seats and can wash out the interior with automatic hoses, all the way up to the executive transport ones that have plush leather interiors, full internet access, and conference rooms. And some people would simply still have their own vehicles to use if they could afford it.
Also, unless you lived WAY out there, say, on an island with only 20 people, or in the middle of Montana with no one for miles... you would likely have some kind of agreement with your neighbors for the car sharing service, so the car might only be a few doors down, and there would be 4 or 5 of them to make sure they were available. If you were one of the 1% (as are many Tesla owners), you probably would have your own car, but that would probably not be the norm.
In addition, I suspect that we should keep in mind that over time people's ways of life will change (kind of like going from a gas vehicle to an electric one)... people will not expect to just be able to jump up and run out in an instant. (like we have to plan better to make sure we are always charged up)
The two biggest hurdles to vehicle autonomy are cost and our legal tort system.
Our legal system is not designed to permit "acceptable failure rates", it is mapped out for deep pockets instead. Tack on additional legal costs, additional safety armor, and the autonomy system itself, and expect a truly viable and profitable autonomous car to operate at a rate several times higher than our existing cost per mile.
Also true... but remember at least in the US, for good or bad, the legal system will often change to handle challenges like this, with limitations being implemented to help shield companies (or people) from liability. When there is enough money on the line, the wheels of justice can move much quicker (though not always in the direction we want them to).
The IEEE says it will take at least until 2040 before we see reliable autonomous cars.
The IEEE is on crack! *(I suspect I am taking their statement out of context though) we are really close now, and I suspect within the next 3-5 years we will be able to see reliable cars that will handle enough situations that they can be considered usable in lots of places. That doesn't mean we will have the litigation and regulatory approvals to allow it to happen, nor that it could (or should) happen everywhere, but the technology is close enough today that I can see it, and I don't see any real problems left to overcome that we don't have answers for... yes, it will still take time, lots of testing and learning, and perhaps more sensors and processing power than we throw at it today, but nothing that I have heard anyone complain about is "technically" impossible anymore.
Cars driven by their owners will co-exist for decades. Question is whether people-driven vehicles will interfere with the whole process of traffic becoming autonomous, will it lead to extra problems. Will we see outlawing people-driven vehicles any time in the future? I don't think so. Too much resistance to change. To start with, a car is an undeniable source of pleasure... not just something utilitarian.
Totally agree, owner driven cars will remain for decades, but I suspect, not that many decades... If we are talking about 20+ years from now, I could see owner driven cars banned from interstates and cities, and if you want to drive, you will have to turn on your autopilot to take you out of the city to RT 101, or US 9, or whatever other favorite driving road you have, away from the commercial routes and paths. (on the other hand, it might make for better driving for the enthusiasts since there would probably be less people out there.)
When making guesses at the future, we need to keep in mind that over time it's not just the technology that changes, social attitudes and society changes as well, and not always the way we would like to see!
There... all done making guesses and judgments that I don't really know enough about to make!