I agree that a big part of the solution lies in retraining -- as a new way of life. In the future, no job will last long. We all must retrain continuously.
But making training the new norm will require big changes to the status quo of how companies retain skilled employees.
First, we need a much better model for skill credentialism. College degrees are way too slow, too broad, and rarely meet the specific immediate needs of business. Some sort of microdegree equal to 1-4 college courses (and more substantial than today's pop MOOCs) sound about right. But their instruction model also needs to be much more flexible and time-insensitive, so working people aren't locked into semester-based schedules. And student social interaction in MOOCs needs to be much improved over the 1990-era forum message chains I've seen.
Second, we need to encourage employers to spend money and time for retraining. And in return, we need to assure them their newly-skilled employee won't soon take their newfound skills and hop to a better paying job. This requires a contract like those between employees/unions and employers in Europe, but largely absent in the US.
Third, employees probably will have to change jobs more frequently. Thus the system needs to make these job hops smoother, steadying employee cashflow to support long-term debt like mortgages, and minimize risks like making health care coverage liquid and independent of employers.
Unfortunately such big changes will require all involved -- employees, educators, insurers, and employers -- to discard their venerated focus on short-term ROI and cost reduction. Unfortunately existing US practices seem almost perfectly unprepared to act gracefully and quickly. While in contrast, Germany, with its longstanding state support for low-cost education, mobile health insurance, union-business partnerships, and skilled jobs that don't require college degrees, seems ideally positioned.
And of course all this has to happen pretty quickly, while we John Henrys can still compete with the machines.