Liberty -- congrats on your 4yr ROTC national scholarship. I'm assuming it's Army? If you haven't, you should DEFINITELY notify US Army Cadet Command that you accept the scholarship. If the appointment to USMA comes through, your AROTC scholarship will be automatically cancelled once you report on R-Day.
Every year there are candidates that receive an 4yr AROTC national scholarship but don't receive a USMA appt, and every year there are candidates that do receive a USMA appt, but are notified that did not qualify for an AROTC scholarship. Different processes doing the selection.
Be proud of your 4 yr AROTC scholarship award. You obviously have a strong record. It typically takes a "SA" quality record to win one. The following numbers are approximates. You probably won 1 of only 600 available 4 yr slots if the AROTC scholarship numbers are anything last the past 2 years. (Army awards approx 2500 scholarships yearly but the large majority are 3 yr scholarships.). In other words, your record was one of the top 600 records Cadet Command evaluated out of around 8000-10000 applications. As you know, AROTC does not have the nomination and geographic component like the SAs and that geographic factor can have a huge impact on getting or not getting an appointment. AROTC evaluates the records, determines a whole candidate score and puts you on the OML in rank order. If you are in the top 600, you get a 4 yr scholarship. That is pretty rare air.
Work your Plan B -- sounds like you've got a great one if the USMA appt doesn't come through.