>Basically, the US military...
Chair force types itching for a new jet.
> Looking forward, they expect this level of weapon sophistication to trickle down to increasingly unsophisticated adversaries.
That is a totally reasonable assumption. I agree that MANPADS may prove problematic. There is the potential to develop countermeasure for these, just not the will, which is a shame because the rotors would benefit from it as well. But, the AF doesn't care for those, either.
>The A-10 lacks the power systems required to drive modern defenses and weapons.
You state this as if it were some kind of objective proven fact. It isn't. It may be the case that some existing weapons system can't be bolted on; but it is not a credible assertion to say that that a suitable solution cannot be developed.
>It is no different than how the US military has been planning for the obsolescence of heavy armor.
It is quite different. Heavy armor is useless, everyone knows it, and to the .mil's credit they are phasing it out. The A10 fills an important CAS role that other platforms can't replace. The F35 definitely isn't going to perform well as an A10 replacement. The Apache works well, but for some reason (sortie cost / availability?) it hasn't obsoleted the A10. Some yet undeveloped unmanned drone might be able to do so, but that is yet to be demonstrated.