It will likely be a mix. E.g. you might have 10 trucks on a particular run. You put a driver in the lead truck, as a human-in-the-loop safety. The rest play duckling to the mother duck.
What it will do is lower the skill level needed, and lower the stress. A driver having a nap isn't a problem anymore. They just need to be able to get involved either if the autopilot has issues and has to stop, or if they need to fill out paperwork at the destination.