The rubber or leather parts will dry out from what I know. Some say the lubricants and oils will dry too, but I not too sure.what will happen to the camera if the environment in a dry box is too dry? Such as 0% - 10% humidity?
I have kept my camera in a dry box with thirsty hippo for the past 4 years. The hygrometer will point to 0% if I am starting a new thirsty hippo. It will eventually go up to 40% after a long time, then I will change to a new hippo. So far, my camera is still functioning well.
I just keep mine inside a bag with some sillica gel. Go out a few times every two weeks to shoot, so dry cabinet not really needed for me.