The thing is that if the position is vital then they rehire. But at least you know that that person is needed. One thing I've learned, for the most part, is that no one person is vital to a company's success or failure. I worked for a project manager that thought everything he did was very important. So he had files and files to document what was happening. He got fired and the "important documentation" ended up in the trash.

People quit all the time and they get replaced. It's the same thing with layoffs. Another thing is that a lot of positions are filled by people that are over educated or experience for the job they hold. They do it simply because that person wants to work for a FAANG and are open to getting any position they can. My suspicion is that a lot of people are going to move jobs as jobs become available and some positions will be merged from say 2 to 1. I'm sure it's crazy now but they will be fine.