As for USAF and COIN there is a huge role. The problem has to do with what gets budgeted for procurement. Airlift and ISR are two of the biggest uses of airpower followed closely by CAS. The USAF has procured a good mix of aircraft for this, but not in good quantities. The USAF ha for some reason been keen to kill of the A-10, but it continues to prove its usefulness. The more interesting example I find is the C-17. C-17 procurement was based on the mathematics of cargo capacity not sortie rate. So even though the 2 C-17's can carry what 3 C141's (whatever it is/the math escapes me at this time) did, the isue now come up of hours on airframes with the C-17 having a higher than forecasted usage rate. Personally, my concern is the apparent inability of the USAF to figure out its tanker procuremtn plan.