Hmm, I'm not so sure.

First, Uber drivers are already not making much. Drivers I've talked to here in SF say they are near $15/hour (though they can more in the form of bonuses if they hit certain hours-driven targets).

Second, the job of a passive driver will actually be both more boring and harder -- you have to pay attention while doing nothing, but be ready to take over in a second. It's like being a passenger, except you can't distract yourself in anyway. I'd much rather just drive.