For long haul you'd still want someone riding in the cab who can do basic maint I think, plus off loading the truck a lot of the times is the duty of the driver. Some companies advertise 'never tarp again!' because tarping your load on flatbeds is the driver's responsibility. Also for in-transit maint airlines need repair, trailer power needs to be checked especially for reefers. I'm not sure about otr truckers but for ltl the driver is offloading trailer.

I can see the training and responsibilities shift as things become more automated, but for what a driver costs, I can't see them getting rid of an incab person for otr trips which leave the city. The response time and costs for fixing minor maint like a broken air line would be crazy. Also someone gotta fill those tanks up.