I also think the managers are scared shitless that the longer this goes on, the more apparent it'll become just how well their subordinates can work from home without their constant supervision. The last thing they want is for the pointlessness of their own jobs to be laid bare for all to see.
Moreover, I fully expect many workers who previously had to suffer the personal expense of paying for gasoline, auto insurance and vehicle maintenance just to make an unnecessary hours-long commute will revolt when the time comes that their employers expect them to start doing so again.
