The Amex lounge is not in the same gate area that DL uses, Priority Pass is. To make the new lounge more convenient for DL flyers it should be in the D30-D40 concourse but is there “free” space to build a lounge?
I am also curious where they would put it. Maybe on top of the gate area?
The Centurion Lounge is a 5 minute walk to the Delta gate area. I always go there for Delta flights, as recently as last week.