There are a fair number of comments dismissing this issue with a "retrain or get left behind" and expressing not a lot of sympathy for those who don't. Remember, the average IQ in the US is just below 100[1]. Exactly what kind of jobs do you expect to retrain these people for? And how are they equipped to pull themselves up by their own bootstraps? Most of these jobs provided on the job training or apprenticeships so…
In reality, it's more like a "death by a thousand cuts".
To give you a concrete example, I work in e-commerce and part of the automation we're building will eliminate 2 full-time jobs on the side of the manufacturer - people who are just entering orders manually, instead of using some form of EDI that forwards the order from the customer directly to the dropshipper. While that sounds insignificant, consider that this is only for a single business relationship between 2 fairly small companies.
There are tens of thousands of companies like this in the US and once those automated systems are in place, those jobs aren't coming back.
Believe it or not, there are still lots of things being done by hand in small and medium-sized businesses, my guess is automation could easily shrink their required labor by 10-15% over the next decade as well.