The Nikon Df was announced 10 years ago – on November 4th, 2013:
Nikon Df camera and Nikkor Special Edition AF-S 50mm f/1.8G lens announcement
It makes sense for the new Nikon Zf full-frame mirrorless camera to be announced prior to the Df anniversary. The initial information I reported back in March was for a fall release:
Also, Nikon still got significant revenue from the Z8 in the third quarter, so it makes sense to release the Zf in the fourth quarter (the announcement could happen earlier).