Again, I don't think this will ever happen, just like we haven't banned horses on normal roads - there's just so few of them that it's not an issue. Likewise, if in 50 years 99% of cars are self-driving, it won't matter an inch if you want to drive yourself in your antique. If you find someone who will insure you in it, fine, go ahead, don't see why they would be banned - self driving cars will probably do a good enough job of avoiding manual cars anyway.
Just like horses which you cannot bring to a highway.
And cities autonomous only? So what about bicycles? Or tricycles? Or hand drawn carriages(rickshaws etc)? Would those roads have high walls around them ,stopping pedestrians from entering?
And finally - where would the money for that come from? Even very rich countries(I live in the UK) struggle to maintain their roads to a high standard, something simple like adding new pedestrian crossings can take years in planning and approvals, but somehow, we would modify all our roads to suit one specific type of vehicle?
I'm really sorry if I'm being cynical, but I really do have a feeling that this self-driving-car utopia is not going to happen.
I think however that at least for several years (decades) the autonomous vehicles must be able to work on the roads we currently have.
As a disclaimer, I would say that I am actually pro-ban of personal vehicles in city centers today. I really do not see a point of anything that is not an ambulance, fire truck, bus, a taxi or a delivery truck on a road. Why people wake up soon in the morning only to then be stuck in an over than one hour commute when a subway ride would take 20 minutes tops is really beyond me.
Banning all cars first and then progressively let autonomous vehicles (as part of a fleet) in would be a win situation in my opinion.
If you are talking about elevated distribution roads that people will pass under, then maybe. But I don't see it working on a city like the ones we have now. Maybe there's a major urban restructuring to happen soon...
Funny, the local SCCA group has autocross at an airstrip near an Amish community. The roads are swarming with horses and buggies the morning of the Sunday events. Interesting juxtaposition :)
+ They will make them cheap. The AI is software, it's a commodity, and the parts (i.e. LIDAR) will be cheap by then.
+ In 20 years you won't likely be able to drive your old car in France, and no offence - they will probably mock the Polish for still having 'real cars' :).
But you're right - 20 years is too soon.
20 years to 'almost everyone in driverless cars'. 30 years to banning humans. 45 years to banning them even from driving hobby cars.
Add 15 years for East Europe and Russia.
Add 30 years for poor places.