The early percentages of people being fired from not being vaccinated are pretty low, seeing anywhere from 3-5% of the workers for these businesses.  What I have read, companies have been able to backfill most positions with vaccinated with little effort.  This sucks, the unvaxxed don't have much of a voice or numbers to fight this.  If you work in a company larger than 100 people, the mandate is coming.  Sad reality with mandates.
Supreme court ruled 100 plus years ago on vaccines, basically saying mandates are legal.  That being said a lot has changed since 1905.  But trying to wait until it can get back in front of the Supreme Court could be a very long time.  
I hate mandates