I can imagine fuel prices increasing, road travel & transport declining in tandem.
The roads will get less repair due to cost and so will reinforce the effect - people don't like bad roads.
Eventually there will be less need to keep the roads fixed because the traffic will be low.
This will be a nasty feedback loop : the roads could get bad quite quickly.
The market for "delicate" high tech trucks will decline, and rugged 4WD trucks like those used in foreign disaster relief efforts will become more in demand ... after all, there will always be SOME heavy road traffic.
We are looking forward to a world of bumpy roads, chunky trucks and bumpy carpets!