In the United States at least, it's going to be devastating. I don't see a bunch of individual owner-operators banding together to protect their livelihoods. As soon as it's cheaper to run automated trucks, they'll get picked off one by one. Probably the best than can be hoped for is laws mandating a person as co-operator in case of emergency. There's also some version of the last mile problem, where people need to be present.
For fully automated trucking, I imagine no one has explored the security implications yet. These vehicles seem far too easy to hijack, redirect, or delay and steal the cargo. Take out the human factor and long-haul trucks are autonomous warehouses roaming the countryside.