My daughter had Michigan, University of Portland and Northern Arizona on her list of ROTC schhols. At Portland, she had to maintain a 2.75 in (5) core classes to guarantee she moved on to upper level nursing. I don't remember the details with Michigan but they also more or less guaranteed you moved up with a certain GPA but NAU is like most California schools. They let in alot more lower level nursing students than they ever plan on taking to upper level so after (2) years, you're score based on GPA, volunteer hours, a nursing related test score and RACE (certain folks get bonus points). If you made the cut, you get to move on.
I actually called the ROTC unit at NAU and asked about the nursing program. Even they weren't too up to speed on how the program worked. I was told that while the ROTC doesn't get any guaranteed slots for those on scholarship, they had never heard of anybody in ROTC not getting to move into the upper level classes.