The assumption that SDCs are going to completely overtake the market is a huge one and is unwarranted. This puts all the cost of building and maintaining a fleet on Waymo, or whoever is first to market. While it cuts out the cost of a human driver, it's not at all clear to me that this is cheaper in net.
Furthermore, a completely robust SDC able to handle all climates and weather in which a human driver is at least nominally competent to drive is still likely a pipe dream. So this model may work well - if it works at all - for the Southern regions of the US, without coverage anywhere else.
While this is true, it's the only proposed path to Uber being profitable. They lose money on every human-driven ride and have no approach to remedy that situation. So if SDCs aren't coming any time soon, or if they aren't any cheaper than human drivers, I'm not sure that's any better for Uber's prospects...
Furthermore, a completely robust SDC able to handle all climates and weather in which a human driver is at least nominally competent to drive is still likely a pipe dream. So this model may work well - if it works at all - for the Southern regions of the US, without coverage anywhere else.