"Over the next 10 years, he said, we need to attract almost 900,000 new people to the industry.
Demographics is a big part of the problem. ATA’s research arm, the American Transportation Research Institute, recently updated its demographic data on drivers and found some 57% of drivers are 45 or older. Only 4.4% are 20-24 years old, noted Rebecca Brewster, president and COO of ATRI."
http://www.truckinginfo.com/channel/drivers/news/story/2017/...
In addition, there will still be much need for humans to take care of the maintenance of the trucks and manipulation of the cargo over the next couple decades. So there will likely be a significant number of truckers still employed, perhaps with increased productivity.
Also, certain other jobs will create large increases in demand for labor over the upcoming decades, in particular home care for the elderly and, if we get politics right, better & more individualized education for the young.
(A reminder) Lump of labor fallacy: https://en.wikipedia.org/wiki/Lump_of_labour_fallacy
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Added in response to some comments below:
Yes, there will be challenges particularly regarding the distribution of benefits from increased productivity. The share of wealth garnered to capital holders will likely increase. People in labor force who have the skills to develop and maintain automation systems will certainly benefit. (That is why education and (re)training are crucial.) The rest may enjoy some, but probably not most, of the larger pie created by advanced technology.
However, the economic pie will be enlarged and there will be more to share. How the fruits of technology will be distributed will depend to a large extent on negotiations and politics.