Indeed self driving electric cars would be a dynamic innovation of near future. But still Im quit skeptical about it. Some of the key cons I think that will effects are..
-electric energy is also among the non renewable source of energy,that may be a danger to our water bodies.
-If may take a professional drivers who can understands how to interacts with the Artificial Intelligence.well that can discharge many jobs out in future.
-batteries stores energy but if something goes wrong with it it may blast,we have seen in past with some of the leading mobile manufacturer including Samsung.
-as you say building a hi tech centralised control system is the biggest challenge of all, I say building a default mode would be the biggest challenge to get car into safe mode if AI can't be able to understand human out there.
The fact is that if society rolls this out on a large scale there may not be a way to stop it. There is a lot of potential in the technology but also a multitude of potential dangers as welll...