But it isn't a pivot in their case. They would be able to make an extremely efficient[1] transition from 100% human to 100% self driving. Uber is not in the business of giving rides in human driven cars - their business is to get you where you are going on demand quickly.
[1] Efficient means money (the first self driving cars won't be cheap and will be limited), but also adjusting to public perception (every crash will suspect the self driving bit leading to a minor backlash) as well as all the other tradeoffs that occur. Someone in the same space with one self driving vehicle won't be particularly useful, but Uber can operate with only one self driving vehicle in the fleet.
[1] Efficient means money (the first self driving cars won't be cheap and will be limited), but also adjusting to public perception (every crash will suspect the self driving bit leading to a minor backlash) as well as all the other tradeoffs that occur. Someone in the same space with one self driving vehicle won't be particularly useful, but Uber can operate with only one self driving vehicle in the fleet.