Re: Let's just say that...
Apples and Oranges
NYC cabs (and taxis in general) operate as individual units all vying to maximize their own revenue. Even when the taxis are controlled by a central operator, the taxi firm has to be careful to evenly distribute work to all the drivers - especially as most drivers are not employed by the firm and directly rely on passenger journeys to get paid.
Taxi drivers are also some of the worst and most selfish drivers on the road - eliminating them will probably ease congestion by 10% alone
Automated taxis will have a completely different motivation model - that of maximising revenue for the owning company.
If ride sharing does take off then automated taxis will come in a wider range of sizes and have a higher occupancy rate greatly reducing the number of vehicles on the road. Try counting occupancy rates in morning traffic. The average number won't be much above 1.
Chaining vehicles may also become possible at some point. So 2 or three automated vehicle couple together and act as one. this further will reduce the road footprint of those vehicles and reduce traffic congestion.