A better thing to say, is that there are no long term labor shortages, in the short term you can have booms where there aren't enough people to fill the jobs but in your example the shortage would last at most 5 years but you'd also have things like better assistance or automation so one person may be able to fill more then one of those positions, you'd probably also have people that could come out of retirement for enough money, or people in related fields that could train in less then 5 years. For enough money on the table you'd probably have people trying to figure out if you can train somebody in less then 5 years. This is also the issue that HB1 visas are intended to solve.

If enough money is on the table people can skill up fast.