Does anyone really think the USAF would want to do so if it was not the best course of action, considering future viability and cost
The USAF was trying to dump the A-10 when Operation Desert Storm arose. Your presumptions about "what the US Air Force" collectively feels or thinks seem to not match what's actually happened.
The USAF like the Army (who recently had to bin the Kiowa Warrior because something had to go, budget constraints) is reviewing all of the kit that it can keep and what it can't, and then balance that against what budget money they think they'll have to work with in the near and mid term.
I don't doubt that "something has to go" is a truth. So, as they did before Desert Storm, they decided that the "something" is the A-10. If they close out that type model series completely, everyone in the logistic, training and operation chain can either be reassigned elsewhere or the billets closed out and a manpower reduction realized. (Another thing USAF has to deal with, like the other services).
As I noted elsewhere, CAS and airborne fires in general are not only delivered by A-10's. They come from a variety of platforms, attack helicopters being one of them. The A-10 is a unique platform that won't be replaced, as it can't be. Nothing does or will do quite what it does.
Does that matter to the Joint Force?
Well, there are enough differing opinions on that to where it very much depends whom is asked that question.
From a strictly functional point of view (which IRL isn't the only consideration) your bang per buck for an A-10 is hard to match.