Costs would at least be lower, which at least opens the possibility of it becoming cheaper. Sure, it's possible to conceive of a dystopic scenario where GooUber has such a monopoly that they can just keep prices arbitrarily high and disconnected from costs, but I think that's pretty unlikely.
It seems hard to say for sure that costs will be lower. The cost of a fully-autonomous/self-driving car is still unknown. Even if google is currently at the 90%, it's well-known that the last 10% is always the hardest. That last bit is especially important when you consider the consequences of imperfection in this venue.
I meant that the incremental cost of paying a human driver would be gone. The fixed cost of inventing and developing the self-driving technology would be minimal because it is amortized across all self-driving cars.
All of that extra cost was R&D, which is currently being funded by Google's advertising. While I have no idea what Google's business model will eventually be with self-driving cars, at the end of the day it's just software and some cameras that can be mass-installed on most any car.
While the cost will initially be higher, it likely won't be much, and will eventually be negligible.
