The real reason is that it has always been the red-headed step-child of the ch-Air Force. There has never been any real interest in the CAS role from the mgmt, other than to keep that turf away from the Army and Marine Corps.
>While the airframe still makes for a great weapons platform, the sensor suites, avionics, and countermeasures are obsolete, and not in a good way. They've been doing a lot of nasty hacks to allow it to support modern weapon systems and electronics but there are a growing number of important capabilities that simply cannot be "backported" to that airframe.
I was about to make a similar comment that the A10 performs its role well despite having relatively primitive weapons / targeting systems. But I disagree about the reason for the obsolete weapons / electronics. Sensors and computers have only gotten smaller and better, and I am afraid I don't understand why you think that the A10 cannot be fitted with proper electronics and sensors.
>This has been increasing its vulnerability to more advanced threats
The definition of a CAS role practically implies that the airplane can only operate in an arena where air-superiority is assured. The A10 is by definition vulnerable to "more advanced threats" and so will any acceptable substitute share similar vulnerabilities.
>Its shelf-life has been extended by virtue of it being used in practice against adversaries with unsophisticated weaponry.
Exactly the kind of adversary it is being deployed against, though it has proven itself against others as well.
>It is a relic of the Cold War not just in its history but, unfortunately, also in its defenses and weaponry with no obvious upgrade path. To replace it with something that could support the capabilities they desire, they would need to design a completely new airframe.
I agree, and I hope they call it the A10-mkII, and that it is practically a modern rebuild of the A10.