First off, the Army is not even considering operating the F-35. They're just saying they are satisfied the F-35 can do the CAS job.
Secondly, even if they were it would never happen. USAF would see this as Army trespassing on their exclusive turf and scream bloody murder. The Joint Cargo Aircraft (JCA) program was an Army program to replace several small Army fixed wing cargo aicraft. The Army selected the JCA configured C-27J Spartan from Alenia. USAF protested saying C-27J was too much airplane for the Army and violated the roles and missions rules. It took only two years before USAF took over the program which they then immediately killed. The 14 aircraft already contracted for by the Army flew directly from the factory to the Davis Monthan boneyard for storage. Coast Guard eventually got them.