rh200
It would seem to be an inertia issue in that case.
The A-10 issue comes down to a few basics, I think.
F-16s, F-15Es and F/A-18s can do effective CAS today, as long as they have a targeting pod (these have advanced greatly in the last 10-15 years) and the right weapons.
The A-10 has advantages - persistence and a large air-to-ground-optimized gun. In some circumstances its low-speed handling and reduced vulnerability to groundfire are important. On the other hand it can't do lots of things that other aircraft can.
How many A-10s does the AF need? Probably not 300. However, as large and as inflexible an organization as the AF is, it's hard to scale down costs with the fleet number.
The other side of the problem is that the AF is now getting an accelerating stream of F-35s - big, complex aircraft with poor (its fans say "maturing") reliability and an automated logistics system that doesn't work. But if the AF doesn't feed the training pipeline now, with experienced MX people who can soon be instructors, it may find itself in a couple of years with a metric
ton of F-35s with appalling readiness numbers. The F-16 force is already feeling the pain.
Chopping A-10 releases a bunch of people who can either be assigned to F-35 or fill the gaps on F-16.