The body would be unable to maintain homeostasis because the cells of the body would have too many jobs to do. The cells likely would not be able to do all of these jobs. It wouldn't be able to live because the organ system helps you breath. The specialisation of cells is paramount to having a functional multicellular organism. If the body didn't specialise then it wouldn't be an organism; it would just be a colony of cells much like those that bacteria and other single celled organisms form.
