After the Coolpix P1000 announcement, there are still four registered but not yet announced Nikon cameras. We already know that two of them (N1710 and N1711) will most likely be the new Z6 and Z7 mirrorless models. The third camera (N1721) will be the new Coolpix A1000. This leaves us with the fourth camera that will have the same radio part as the D3400. Maybe this will be the rumored D3500? It is still hard for me to believe that Nikon will set an event before Photokina only for the D3500. There must be something more.
The Nikon D6 is rumored for 2019 – the D6 trademark is already registered (there will most likely not be a D5s).
A new high-end compact Nikon camera is also still a possibility.
Rumored Nikkor lenses:
Here is the list of four registered Nikon cameras:
Via Nokishita, PhotoRumors