Most A-10 CAS is now delivered from middle altitude via PGM.
Having spoken very recently to serving A-10 pilots with operational experience in Afghanistan, I can assure you that this is not correct and that the gun is still very much the weapon of choice across the Warthog community.
A point also made by a USAF F-16 pilot I interviewed last year who quipped that the third word to come out of every A-10 jockey's mouth is "gun", regardless of the topic of conversation.