It could. It could also go from one-point-something to zero-point-something. Until now, the floor for car occupancy was 1. It's now zero. There is the possibility of empty trips (repositioning for next shuttle run, driving to distant parking lot, etc) adding rather than subtracting traffic.
I agree that a certain amount of repositioning trips is likely, but I also expect that they will be calculated for when they are fastest and cheapest. Even in an all-electric-car-all-the-time scenario, fuel isn't free and sitting with the engine off is easier on the car than idling on a highway.
