The Nikon D500 DSLR APS-C camera is currently out of stock or back-ordered at Adorama and B&H Photo (limited availability at Amazon):
In Europe, the D500 is also out of stock at the major online stores: WEX Photo, Calumet DE, Calumet NL, Foto Erhardt, and Foto Koch.
In Canada, the D500 is listed as “on order”.
Update: the Nikon D500 is also listed as discontinued at Nikon Asia (see link): http://nc.nikon-asia.com/en_NC/product/discontinued/digital-slr-cameras/d500
The Nikon D500 is listed as discontinued at several stores in Japan – the first screenshot is from Yodobashi Camera (the D500 is also no longer offered in the Nikon DSLR catalog):
Bic Camera has also listed the Nikon D500 as discontinued (D500 is out of stock at all listed stores):
Map Camera lists the D500 as “back-ordered”:
The official Nikon Japan store is also no longer accepting orders for the Nikon D500 (via Dclife):
The Nikon D500 was announced back in January 2016:
A while back there were some rumors that there could be a new high-end Nikon Z APS-C mirrorless camera to replace the D500 but I have not heard anything since.