Do you loose those NRT route authorities after a period of non use?
Yes you do, Nitty . . . . I was once told that FedEx had used an empty C-208 Cessna Caravan at NRT, just to operate a daily landing so as to keep their NRT slots (not sure of the validity of this).
Polar's PVG slots are also now in question . . . if all true, watch as AAWW's stock tank's even further.