On its way out

Like stamp vending machines and blue street mailboxes, the Postal Service will begin removing green relay boxes, where carriers store mail during delivery, due to a decine in first-class mail. I've seen only a few of these relay boxes, and I didn't know they were actually in use until I read about them a few years ago. I thought they were old regular mailboxes that were never removed, like the police and fire callboxes in DC. Will these find new life on display at the Postal Museum, I wonder? Be auctioned off? Taken near Kingman Place, NW DC.