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:
If the Nikon Z6 III camera is coming soon, I have not heard about it
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).