Nursing schools cannot attract a greater number of able applicants than they currently do unless the problems of low ...

I am trying to understand why the last sentence "It is clear that with either a shortage of nurses or lowered entrance standards for the profession, the current high quality of health care cannot be maintained" was diagrammed as conditional; i do recognize the either/or, and in one of the examples showed, the sentence with an "either/or" was not diagrammed as conditional because there was no conditional indicator.