And when there is a swift to driveless cars the business model economics is totally diferent, Uber will have to spend billions on a fleet, drivers costs will be replaced by fleet costs.
This would be a best-case scenario for them. While personnel costs will stay the same or increase fleet maintenance costs will only decrease over time as driverless tech gets cheaper. If they get to the point where their dominant cost is maintenance of an autonomous driving fleet they will have won the competition for the future of transportation which is today in its infancy.