At a bird's eye view, retraining has happened many times and will happen many more times, but it's always been done by individuals acting by themselves, I'm not aware of any civilian retraining program that's worked on a large scale
you can safely write off every single politician who talks about retraining as a solution to industry disruption, this will not happen, this has never really happened, it's fiction. maybe there are ways this *could* work, but in my more than two decades of working *in training*, no one's ever tried