In this day and age of budget cuts, including the fact that they will be closing dozens of units, I would say do not enter from a financial aspect of receiving one to pay for the remaining 3 yrs. There just is too much uncertainty.
This yr they brought back the IS and many posters did receive the 3 yr., but remember they will be looking at your SAT/ACT too, so if you have a low SAT/ACT I would suggest you take it now this spring so you can increase your chances.
Remember the AFROTC cadets that did not get HS scholarship will try again next yr too.
Everything matters, and if you strive for 110% 100% of the time your chances will increase, but always, always have a strong Plan B in place at all times.