Making any picture as light BW is impossible. But if there's well selected colors, they can be turned to nearly white in BW mixing. Let's assume all walls and floor are green and with well directed lights and material selections there's no green on the people and other objects which really are in studio. => you can treat the walls and floor separately.
A fake example (This popstar maybe hasn't as slick outlook, but with the same amount of AutoTune his singing would stay as well in pitch):
Desaturating the image gives this:
But color selective BW mix gives this:
Note1: In studio the light on the objects really must be able to supercede all green reflected light
Note2: Red objects could as well be mixed to black or white without spoiling the Popstar because there's no well saturated red in him.