A mental model for disaster here is tenure-track hiring in academia. Almost every school down to your least prestigious 4-year state university hires its faculty from the same top 50 or so places. All the graduates from the thousands of other schools have to leave academia or work as adjuncts or postdocs. It's possible that these layoffs are the equivalent of releasing all of the graduates from the top schools into the market, locking everyone else out or pushing them into lower tiers of jobs.

The questions I suppose are whether there are enough jobs to absorb the newly laid off workers with minimal disruption and whether mechanisms exist to move the workers into those jobs. Your 4 million includes irrelevant positions like IT help desk at a doctor's office in Omaha, which would be a bad match on both sides and even if it weren't would be hugely disruptive to the employee and others.