When people ask, “who will build the roads?” my usual response is, “the same people that currently build them, it’ll just be financed differently.” Then I go on to give a few quick ideas.
Tolls are an obvious choice but so are trade associations that want you to visit malls and stores. Perhaps non-profit organizations pop up to facilitate the easier movement of people and build the roads? Maybe we will all start riding on drones or using other technology. Maybe unions or employee associations charge fees or payroll deductions from your paycheck in order to maintain the roads needed to access your job?
Point is, I don’t know the solution, I do know a solution exists and would become a reality. What won’t happen is the government stops funding the roads and then the world descends into chaos, no business gets done and people live solitary lives and never leave their home other than maybe walking to a neighbors. This, I am confident, would not happen.