I think many of us in the 'modern industries' have to spend a good portion of our lives relearning everything. We either do it a bit constantly or find ourselves outdated and struggling to make giant leaps because our skills are no longer 'needed'. I have seen this in everything from automobile shops, textile plants, chemical factories, government bureaucracies and even farming. The only way things stay the same are when they get artificially 'protected' by a large enough society forces their government that they are willing to keep say XYZ cheese making exactly the way it was done in 1420. [Usually whatever it is has to tie deeply into national pride and have been going on for hundreds of years to get that mark so at this point steam powered computers is probably the only thing which would get this point (sorry Cobol)]

Otherwise we find that we are relearning things all the time or being replaced by someone younger who is 'up on the new things'. Then we have to fight with others in the 'heritage' pile where there is an oversupply of people and undersupply of jobs. Then the only way to shine there is being a consultant who can sell themselves better than the others and command that price you want. However usually that also means being up on the new things enough because you are going to be transitioning whatever 'heritage' to something new enough to find less expensive people later.