Having managed and laid off people (unfortunately), I would guess middle managers have already been given a number X to cut already, and they are spending some sleepless nights already trying to figure out exactly what to say (unless they are too chicken and have HR personel do the firing)
That is only one of the ways it’s done. The other is to hire strategy consultants who analyze org structure then try to fit people in those remaining boxes. Those left out are really out.
I always definitely know because I explicitly ask, and recommend others do as well. It was one of the things I started doing after reading through Netflix's culture deck.