Were you even alive in 1991? The first shots in Desert Storm came from F-117's flying out of King Khalid Air Base in KSA, and Tomahawk cruise missiles from USN ships in the Persian Gulf.
And AC-130's are great, but they won't fly under a cloud deck and neither will F-35's, so your troops on the ground are SOL if they need CAS and it's not a sunny day...
Little boy, I retired from the United States Air Force and was part of the training for Desert Storm. I just let you in on something that was not widely advertised that allowed the first choppers and A-10s to cross a certain line un detected. And the AC doesn't need to fly UNDER the cloud deck. That cloud deck helps to hide him so he can come a little lower and get even a more defined picture.
I came up with a saying for the A-10. ICUUCMe. Meaning both sees each other and both can shoot each other. This is assuming that air superiority has been accomplished. The normal A-10 attack is from 10K to 20K with guided ordinance. And he's not very good at that so he fires a lot of it. Not the most pinpointed method ever seen. The AH-64 is a better pick for close in since that is what he was designed for. But from 20K, the AC can hit a running man every time. Destroy a specific vehicle out of a convoy, or level a cement warehouse and then move off to his next assignment without returning home.
The point being is, with the fighters being able to handle the long range attacks, the AH-64 and the AC-130J more than able to handle the up close and personal why do we need the A-10? Remember, we've used the B-52 for CAS as well when needed.