They can't, they are speculating.
However, I would agree with the det. Be prepared to read this a couple of times because it can be confusing.
If they re-open IS for Fall 12, that would be FY 12-13. The class yr would be for 15 and 16, assuming 3 yr or 4 yr (engineering). Now look at what is currently going on.
Class of 12 and 13 took hits because they reduced SFT drastically. 14 and 15 have had less scholarships offered. 15 AFA will have less apptmts, and OCS was canceled until this past Jan. That means next yr at this time if they lose too many they will need to re-fill the pipeline with 15 and 16. Remember you can't come into the AFA as a C3C. Plus, OCS is going to put them in the pipeline now, not 3 yrs from now. Thus, if you need to get back on target for officers you would re-open the pipeline.
Now, let's be honest, the fact is due to this economy even if they re-open it for FY 12-13 (which in essence would be the budget 2 yrs from today), nobody knows if it would 5 or 500 scholarships.
Det commanders are traditionally O6's, thus, I would trust them. Impo I would not believe what the flight commander says because they are usually O3, maybe O4. The FCCs probably have never experienced force shape re-structuring. The O6 was around for the infamous 92/93 RIF. They get it. They can see that right now the classes in the cross hairs are 12/13 and 14/15 is on the cusp for ROTC. The engineer for IS in FY12-13 could be 16. By that time they could see that the AF will be back on track.
I know that was confusing, but like I said re-read it, and once you start to understand manpower needs are tied to commissioning yr groups you can understand why they can say next yr they will open it again. Also, remember they can re-open it and offer 1 scholarship, but they still offered that 1 scholarship...sim. to the VP apptmt to an SA. 1 of those candidates out of 10's of thousands will get that apptmt.