Hi Joe —
It is about the demand side of the equation. Uber has itself in a position with a ton of demand. Filling in a new form of supply is relatively easy compared to the cost of building the demand. This is what most people miss when they think about these future networks.
As far as 2020 and drivers abandoning a platform that has AVs, the new AVs will cost consumers less (as long as they are fully utilized — going back to demand). Like workers in endless other industries (automotive, shipping, railroads, retail, banking tellers), there will be attrition from driving and shifting to other careers created by the new cheaper, more convenient transportation service. There is even a scenario where the demand goes up or is flat for drivers — or “people who assist in coordinating the actions of a vehicle” since they won’t be driving most of the time or at all. That has played out with bank tellers and ocean shipping labor.