I think we will see autonomous cars on our roads before this happens. Even so there will be humans watching and at the controls incase they need to take over. When lots of money is at play I doubt anyone would risk it on machines doing everything.
Time frame? 15-20 years many industries will be autonomous. But then where will the people work? No work no money no buy stuff. There is kind of a symbiotic relationship with consumers and manufacturers right now this automation may screw that up.
Yes i agree autonomous cars will definitely be on the roads, Elon Musk has teased that level 3 autonomy is mostly finished and needs small refinements before implementation in all Tesla vehicles before the end of this year.
Your second point is something I don't understand, statistical studies have shown autonomous systems, even now, are far better at processing risk and reacting to it than humans. Having a human 'watching' is pointless. In the case of total system failure the autonomous system would be programmed to simply pull over and wait for assistance. Management is based on statistical evidence, which is why firms today implement as much autonomy as technology of today allows for exactly the reason of limiting risk. The biggest risk to any system is the unpredictability of humans.
As for your point with jobs, I do agree that in the short run job loss may be a problem. But you have to realize this type of thing has been happening for centuries. Not too long ago most of the population was required o work in agriculture in order to feed ourselves. As agriculture became more efficient people panicked about jobs being lost. Instead other industries grew to provide employment. firstly their is the direct employment of industries that develop and service the autonomous systems. Secondly autonomy will drive down the cost of goods, meaning consumers will have more disposable income to spend elsewhere,for example service industries or entertainment industries.