The elimination of roads in favor of elevated rails and underground transit tubes will necessitate the complete redesign of cities. Fortunately, since most cities will have been either destroyed during the war or abandoned due to climate change, this will be a far easier task since new cities will have to be built rather than existing ones modified.
If materials science hasn't made giant arcologies feasible by the time the war happens, then the postwar period will be marked by cities built around central train hubs, with light rail lines, high-speed lines, personal rapid transit lines, subway tubes, vacuum tubes, and commuter rail lines extending outward like spokes on a wheel. PRT lines will be used in low-traffic areas as well as complement high-traffic areas. Light rails, commuter lines, and subways will meet high-traffic demand. High-speed rail will meet demand for rapid transit within states and provinces, while vacuum tunnels will meet the demand for transcontinental trips. Hypersonic jets will cover world travel needs while vacuum tunnel technology catches up.
Once materials science makes gigantic structures feasible, and room-temperature superconductors make hover technology a reality, massive arcologies will become commonplace. The bulk of cities will be contained within one huge structure, while the surrounding land will be primarily residential. Even residential areas could be housed within the main structure, so long as the needs of humans for yards and fresh air are met. There could even be hover cities akin to Cloud City, if quantum levitation becomes practical. The citizens of the cities will get around via a network of elevators and vacuum tubes, while trains and jets will facilitate travel between cities until human teleportation is perfected. Our solid trash will be recycled through 3D printer/disassembler hybrid, while our bodily waste will be used as fertilizer for urban farms. We will use far fewer resources, which will negate our impact on the environment.
And our descendants will finally be able to repair the damage we have caused...