The Air Force has been trying to kill off the A-10 for 20 years. Back in the 90s, there was an Air Force General (maybe it was Horner) who suggested transferring A-10 operations to the Army, and in exchange the Air Force would take over the Patriot Missile System. It made perfect sense, but the Army didn't want to give up their missile defense capability.
So far, the F-35 is proving to be a real lemon and a very expensive one at that. When the U.S. got involved in Vietnam, the Air Force thought its jets could handle the close air support mission. They had to turn to the Navy and acquire their Skyraiders for the close support role. By dumping the A-10, the Air Force is showing they didn't learn from history.