The A-10 close air support plane will be available to support ground forces for at least a decade more. Eventually they will wear out, but they will be kept flying.
Now I'm okay with the idea that we need cheap planes that can drop precision bombs in a permissive air defense environment:
Air Force Chief of Staff General David Goldfein agrees that Sen. John McCain’s recommendation for “300 low-cost, light-attack fighters” is a “great idea.” Analysts have noted several merits including stemming the decline in platform numbers, improving dwell times over target areas, lower flight hour costs, and more stick time for USAF pilots. These are good things. But the real issue is the substantial ongoing attrition of 4th-generation airframes that will only partially be mitigated by the light-attack fighters after they’ve arrived in inventory. That’s why we need them now. [emphasis added]
We are using expensive aircraft to drop bombs on insurgents, terrorists, and light infantry. This is wearing them out without replacements in the pipeline. We need those numbers.
The most important things we can do in an era when we are dropping 26,000 bombs per year even though we have "responsibly ended" our wars while shifting our emphasis to high-intensity conventional conflict is to save the lifespan of the planes needed for fighting a war through the opposition of enemy air power and air defenses.