Nikon already many of the core parts for more high end cameras, including: EXPEED7 processor, Z9 AF and EVF code, CFExpress media is now the new standard. The company has no option but to prioritize high performance cameras at both ends of its Z System: DX (Z90) and FX with high resolution sensors and/or Z9 spec AF. The Z50, Zfc and Z5 are already out in the world to grow up its client base. The question at the crux of Nikon's future cameras is how quickly will they upgrade their "primary core MILCs" to stacked-sensors to handle the Z9 blackout free EVF and AF (i.e. Z6 and Z7)? This may be too costly, but it's one way way to sell more Z9 sensors - so the Z7 is more likely to go stacked first.
The possible stand out features of a Z8 (or whatever it's called) will be to extra high resolution for genres seeking high resolution that otherwise is in Medium format: Studio and Landscape genres. Thus 60mp or more FX sensor possibly extended with pixelshift. It's unclear if this camera requires a stacked sensor if it's also to do 8K and handle the EVF specs etc.
The incentive for the Z90 is the impatience over lack of a D500 "equivalent", and a more affordable MILC for action genres, which can also deliver excellent 4K video. Nikon must have known nd already acted on the future trends for DX MILC's many months ago. Thus Z90 must be an urgent priority, because Fujifilm already has its
stacked DX sensor in the
X-H2 due in 2022, possibly May.
There are few if any crippling gaps considering the combined F and Z Nikkor lens systems, but at least 3 categories in the Z System are standing out more and more .......glaringly, there's no Tilt-shift, Macro-zoom (70-180), medium telephoto zooms (70-200 f4S, 70-300) - all Z mount.
Last but not least, Nikon has the Z mount, the future on which they are rapidly building their future. Its strategic features no longer holds back their mirrorless system (no dual DX/FX mounts, the architecture is not restrictive etc)
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