You can move more people by getting some of them to take transit or ride bikes or walk to work, though they are quickly replaced on the road by enough cars to keep the speeds more or less the same (induced demand again).
Did this guy just make the argument that shifting people to cycling and public transit just induces more demand for driving? What a profoundly stupid idea.
Shifting people to active and mass transit options requires making those options more efficient than driving. It means fighting and winning a god damn war on the car; taking away space from cars and giving it to active and mass transit options. At a certain level it is a zero sum game. So no, after the shift to bikes and not just bikes, cars are not coming back.