For 2018 Nikon is rumored to announce at least two high-end/professional grade cameras and at least two lenses. I assume that at least one of those cameras will be mirrorless. Nikon already has three new cameras that have been registered for a while with various government agencies but are not yet officially announced. A replacement for the Nikon Coolpix P900 camera is also long overdue.
Two new Nikkor lenses are rumored so far: 600mm f/5.6 PF and 60mm macro.
In the past 12 months, Nikon has announced only one camera – the D850 (the Nikon D7500 was announced on April 12th, 2017).