Fairchild Republic has been out of business since the '90's. The Hagerstown plant where the production A-10s were built has been closed for over 30 years. The subcontracting companies that made the parts have long since crumpled under the weight of Pentagon procurement and the dust has blown away.
The only thing that is keeping them flying is that the aircraft was built simple and strong, for field repair and fast turnaround, without, oddly, all the Captain Midnight fly-by-wire the pilot/procurers so dearly love. Control is siamesed hydraulic systems, with a manual backup.
Consider this. The aircraft is designed to fly with one engine, one tail, one elevator, and half of one wing missing. However, there is no way there will ever be another A-10C built.
On top of which, the tooling was destroyed by order of Congress.