IIRC, the linebackers have been withdrawn from service
Yeah, the Army had decided that they were not needed; as noted in the article, they had decided to de-emphasize ground air defense against aircraft. However, as the article also notes, the Army is now hastily revisiting the issue. The M6s were “withdrawn” by bringing them into depot, swapping the Stinger missile pack for their original TOW missile packs and updating the software; the Army is now seriously considering reversing that as of this year. http://breakingdefense.com/2017/08/laser-in-front-grunts-in-back-boeing-offers-anti-aircraft-vehicles/