More people will die horrible deaths in their cars, more people will die walking and cycling, more people will die because their understandable fear of walking and cycling gives them a sedentary lifestyle, more people will die from cancer, lung disease, etc, more wildlife habitat will be destroyed, more sound and light pollution will destroy mental health and disturb wildlife, and the planet will boil a little bit sooner. But those are externalities and not borne by the person choosing to drive more.
But all of this is apparently just fine. Adults matter too of course, but it's striking that cars (drivers, really) are the thing that kills more kids than anything else, and yet people do. not. care. I'm astonished how much outrage there is over kids being killed by bullets but not those killed by cars. People in the US accept it as normal, though. When I pointed out I cared more about automotive violence than gun violence people would look at me like I had 3 heads. And then joke about running over cyclists.
On the bright side, it might encourage those who are able to emigrate somewhere nicer (Netherlands and the Nordics, basically), so I guess it's a gain to those countries.