Whether it is car, bus, train, Uber or hovercar, we will still need roads. Until personal jetpacks and flying school busses are a thing, the road issue is totally divorced from the type and environmental impact of vehicles driving upon the. Some form of road will be there regardless of the means, or even the amount of traffic, so long as a connection is needed.
Of course we need roads. We just don't need all of the roads we currently have; many could be (and were, until very recently) eminently more sustainable forms of mass transit. Similarly, many of our roads could be narrowed and augmented to induce demand away from unsustainable development patterns.
The thing is that we choose the amount and type of traffic and therefore the physical size and area of our roads by planning choices that induce behavior.
“We will still need roads” is true, but the amount and size of those roads are important details. Not all roads are created equal - just ask your local bike path how many animals were killed in collisions.
But there are at least two problems with such a deceptively simple statement:
1) Road construction is constantly expanding. They create their own demand by diverting resources away from many things including affordable housing -- the number of people I know that commute for over an hour because they cannot afford to live near their work is non-negligible. At some point this becomes a planning/resource issue and at the moment the decision is to carry on as usual with a system that is causing major problems.
2) The amount of traffic makes a huge difference. It is well documented that roads create ecological bubbles affecting animal populations negatively. The speed and frequencey of the traffic (type of vehicle) makes a difference.
DDT in very particular situations has also been a net positive. It's really the widespread indiscriminate use of it in nature areas and dumping it by the ton into municipal sewers that caused the terrible ecological outcomes. Similarly, organising ourselves into sprawling suburbs (rather than higher density cities with sparse rural communities and nature areas in between) was ecologically, the less optimal deployment of roads.
