The economic re-allocation doesn't have to be overnight or even in a single decade. It isn't as if the revenue suddenly goes to zero and the industry is nuked.

No matter how long it will take they will have to start fresh and whatever experience, knowledge and education they had becomes useless. Much more likely they simply become unemployed and stay that way.

That is an awful lot of time wasted of their lives.

It doesn't. Some people retire, some people leave the industry because they prefer something else, etc. All that needs to happen is that not all of them are being replaced.