My assumption would be that you will owe the 4 yrs like any other non-rated ROTC grad. Of course you can always try to apply for an ED slot if not selected for rated.
The thing you need to realize is that when you go up for rated it is 4 slots. Pilot, CSO, RPA and ABM. You may ask for pilot, but get offered RPA. On top of that, not everyone will wing out of UPT, actually a nice chunk won't make it, however they are still on the hook for the commitment time of 4 yrs. ADAF
~ This does not include if they have to send you to a school. IE they send you to Intel school, then PCS you. That clock(PCS) starts again when you arrive at that base, but it runs concurrent with your original ROTC commitment. IOWS, if you wash out at UPT 2 months before you wing, then wait 4 months to start a new school that takes 6 months to complete, that yr counts toward the commitment, but because you still owe 2 yrs they are allowed to PCS you for a 3 yr assignment. You now owe 5 yrs ADAF instead of the original 4 from a non-rated world aspect.