Uber could still offload maintenance, fuel, liability etc to other entities and license the self driving software to them. Those entities would still have much lower operating costs than human drivers. They could even open source the self driving software to commoditise their complements [1].
Personally I hope that regulators do a bait and switch on Uber by allowing them to build a temporary monopoly and then reintroducing competition by introducing the "right to be represented by a bot" [2].