Even if they could be converted (and most buildings after a certain height are basically the same except for the interior) they'd likely be torn down and rebuilt; if they even can be due to zoning.
People love to hate on zoning but there are reasons for it, even if the way it's done isn't perfect by a long shot.
Commercial leases can't be repurposed that quickly, and I suspect a lot of companies are holding off on doing anything different with their office space. If the past two years have resulted in permanent change, then some office space will likely get repurposed, but it's too early to tell whether it's permanent, and nobody wants to jump the gun and get it wrong.