There is currently a shortage of drivers and teh average age is rising every year, the ones currently in the industry will stay and can move from job to job as they please, it's the youth who will lose out on the job prospects and their pity is naively misplaced..
Trunk work may drop off in 15 years if they can get bigger trailers allowed and reduce the break regulations but overall delivering anything to anywhere outside the main purpose built depot off the motorway needs a human. Taking a vehicle that will regualarliy need to drive on the wrong side of the road due to the physical size constraints of the UK road network and unload itself, if it can make those decisions then it's not lorry driving but just about every job that will be gone.
There was a video about an automated forklift installation where the moajority of employees were forklift drivers, the company is growing so again they don't fire the 10 guys they have but instead use robots for the new work. Where it would have been a 16 hour shift on Monday, not much to do the next 2 days and a massive amount of work on Friday/ Saturday which previosuly would hav needed 2 new employees to cover the highs and lows they just get robots to replace them, where it's subtle or complex work that requires any kind of thought they keep the humans on.