I'm skeptical about the timelines of these reports. Certainly we'll never see all 1.8 million drivers lose their jobs overnight. These guys are predicting auto-truck apocalypse in 5-10 years, and we still don't have a single commercial system on the road that's capable of even lightening the load on a driver, much less replacing him. I think truck automation will go in 2 ways at the same time, and we can watch the progress of each:
Systems to ease the strain on independent drivers. Ones that can cruise on the highway without supervision indefinitely, but need help with city streets, parking, maintenance, loading and unloading, keeping manifests, dealing with whatever company is loading and unloading the cargo, etc. They may need somewhat fewer of this class of driver, since the trucks will be able to run more continuously and there will be less need for second drivers and probably fewer trucks. Motels and truck stops will hurt some when the truckers can sleep while the truck drives instead of stopping. I think we're at least a decade away from this existing at all, much less being common.
Full automation for tightly integrated logistics chains. Maybe the Wal-Marts, Amazons, Fedexes, and other huge companies that own the entire logistics chain will be able to figure out how to use fully automated trucks, that can drive from one company facility to another, complete with parking and maneuvering, driving local streets, and letting other company systems handle the logistics of loading and unloading and keeping track of what items are where. I bet at least one of them will start experimenting with something like this in the next 5-10 years, but probably at least 20 years before it works well enough for them to cut down on the number of drivers they employ.
There will be job losses, but it will be slow and gradual. There should hopefully be plenty of time for the economy to adapt, and hopefully either create new jobs for all of these people to do, or move towards something like UBI. I think we'll have to have a massive cultural shift before anything like UBI would be considered or even possibly make sense.