I guess we learned that lesson pretty well with Obamacare. Hundreds of private insurance products got reduced to three, simply because the Emperor said so.
Those former machinists should now be doing something else that computer-controlled machining centers cannot do. If they are smart enough to be machinists, that shouldn't be a problem
There are two problems right here:
1. There is not enough demand for machining in the whole world. One machinist can supply all the parts. Other machinists, even if they are capable, are not needed. There are no even mills for them to work on. You can say the same about every job - there are only so many stores to be a clerk at, so many banks, so many fast food joints... even writers compete for reader's attention. The manufacturing can be so efficient that it floods the market or runs out of the raw materials.
2. Not everyone is capable of learning the higher skill. What if the new machines have to be telepathically controlled, and only 20% of the population are capable of telepathy?
There is no known solution to this problem. Currently the USA is using a passive approach of supplying the unlucky workers with some minimum money, so that they don't grab torches and pitchforks yet. This solution is a social poison, and it doesn't really solve the problem. For example, in the near future all stores will be online, ran by computers; all services will be automated; where will a common man be employed at to earn money to buy all those goods? These goods are not free, as in Communism - someone has to invest into those automated factories, and some people will be working there, if only to maintain the machines.
The worst part of this problem is not even money. The absolute worst here is the fact that tens of millions of workers will be sitting at home for weeks, staring into the telescreen, and eating Ramen noodles. Can you imagine what that will do to their mind? It is perfectly clear why ghetto kids do all the crime. Idle hands and all that. Even if we manage to skip to the ideal Communism, where robots do *everything* for us, the human society will go crazy.
Back in the day, a far larger proportion of the US labor force was engaged in agriculture than today.
For instance, in 1921, Philo Farnsworth, aged 14, was plowing a potato field. He looked down at the tracks left by his disc harrow, imagined an image overlaid on the field and tiny electrons representing the lightness and darkness of the image at each point in the field, and invented TV.
Over the years, mechanization decimated farm jobs, but TV and similar replaced them and greatly improved the national wealth. Over the years, we needed far fewer farmers and a lot more other types to support our upgraded lifestyle.
There is no way government bureaucrats or late night internet posters could possibly have figured that out. But it nevertheless happened.