Maybe that's a good reason why we should be supporting a broad based curriculum in college at the Bachelors degree level, rather than specialization. If a worker has a solid liberal arts education (not to exclude math and science), then it shouldn't be all that difficult to retrain for a different career on an as needed bases.
Many masters degrees can be obtained in a year or a year plus a summer, assuming that the student has the prerequests for that masters. And a associates in a particular field could probably also be acquired in a year, if the student already has all the general ed requirements. In today's world, an employer might advertise for someone with a BS in a particular subject, but may be perfectly fine with hiring someone who has an AA degree in that field as long as they also have a Bachelors degree (in anything).
Few working adults who find that their job skills have become obsoleted are going to be very enthusiastic about starting from scratch and attending college for four years. But if they could obtain education/creditials for a different field in a year or so, it's goint to be a lot less intimidating to them, and a lot more doable.
All of this is why I believe that the Bachelors degree should be a broad based liberal arts degree, taking a course or two in just about every subject one can imagine, and allowing the masters degree to be the "major". Lot's of colleges now offer "Bachelors of Interdisciplinary Arts", and it sounds a little hokey, but it makes a heck of a lot of sense for someone who is grad school bound.