You can't ever really get rid of the roads, you can only downsize them. Even if everyone uses public transit, you need some way of transporting goods and cargo

You can't ever really get rid of the roads, you can only downsize them. Even if everyone uses public transit, you need some way of transporting goods and cargo, and the only way currently of doing that within a municipality or to most final destinations is by truck. Whether you're moving a shipping container full of stuff to a retail store from the train terminal, or you're packing up someone's home and moving their furniture to a new apartment, it always goes by truck, and trucks need roads. But if we could get rid of cars, we could make the roads a lot narrower.