For obvious reasons, you're not going to see mask mandates for flu season. It's simply not contagious enough. I think there will be more social pressure to wear masks when you're not feeling well and an increased acceptance of staying home when sick though.
I think it'll be more a matter of "I don't want to get sick and I'm your manager, so {put on a mask,stay at home until you're no longer sick} or stay at home forever".
This is indeed how it works for the healthcare industry; when I was doing hospital IT, my choices during flu season were either 1) vaccinate, 2) wear a mask, or 3) find a new line of work. I picked the first one.
