Nikon has maintained momentum since inaugural launch of their entirely new Z system. The Z9 will make a total of 8 Mirrorless cameras.
30 Z lenses will be out by the end of this 2021 Financial year ie April 2022. All within 3 & half years...
A 85mm prime, the 200-600 and the two telephotos are remaining.
Of which, the fast 400 S is likely to be announced as in development.
This bigger gaps is the niche of prosumer cameras in a price range under the Z9. At least 1 of 2 cameras are absent:
1. the Z8 highest resolution ie 60mp at least
2. a Z90 will be more cost effective to produce and sell at an accessible RRP. Built around a DX Stacked-sensor, and cloning across Z9 algorithms in a Prosumer DX MILC. Thom Hogan has mentioned Nikon had been planning for a high performance DX Z MILC aka Z90
Both with optional vertical grips in addition to expended Menu and Controls ie Shooting Banks with much improved Customization options.