Taking this one step further - do you think Nikon will offer many more MILC (pro/prosumer) cameras than they offered in the dSLR lineup? If so, what additional segments do you think they will address/features provided? D500 replacement for sure. Lighter version of the Z 9, could that be the Z 7iii or does the line have such a bad reputation that they will switch to a different name? High megapixel camera beyond 45 MP? Would that be the role of the Z 7iii? I don't see NIkon offering both light Z 9 in 45 MP (Z 7iii) and a light 60 MP camera (Z 8). I can see a 60 MP light version of the Z9 in the future. The sensor would be then used in a D500 replacement (60 MP FF, 26+ MP DX mode)
Or will the Z 9ii be 60 MP?
Thoughts?
One of the key points of Nikon's 2018 reorg was to have more sharing of components. They demonstrated that with the Z6/Z7 and Z5, the Z6ii/Z7ii, and the inner working of the Z50, Z50, and ZFC. With the Z5/6/7 series the outer body is the same, the battery is the same, and most of the functionality and menus are the same - just the sensor and directly related functionality has changed. The same is true for the Z6ii/Z7ii - two flavors with essentially the only difference being the sensor. With the DX cameras, the internal components are largely the same but they look different. With the Z30, they tuned the camera and some specific features in a different direction, but they did not start from scratch. All this is to say it would be relatively easy for Nikon to continue that approach with different flavors of similar cameras and unique positioning or tuning.
I don't think Nikon needs to have lots of cameras that lack differentiation and specific market positioning. There is no reason why I can't change cameras like I change lenses and target specific situations. It may be cheaper, and certainly allows redundancy I want to have. I avoided the D750 because it was an economy model compared to the D500 and D850 - even though a standard resolution camera was appealing. I really like having the Z6 for standard resolution and the Z7ii for high resolution. I think at this point, most people are looking to add an action camera and possible higher resolution video. There is room for high resolution, standard resolution, and DX flavors of action cameras.
There is limited additional value in 60 MP given the presence of 46 MP. The advantage of 46 MP is it gives you 8k video. In addition, it gives you video and still cropping to standard resolution. That's like another camera. If you want high resolution, Nikon needs to go farther and think about 80+ MP. I'm not sure there is much value, but the processor speed and lenses are good enough to support higher resolution so it is possible.
Perhaps a way to think about this is based on AI enhancements. Computation capability is really the key. Look at how much you go to third party software for post processing. Some of that is low hanging fruit for the camera companies. Here there are two paths - creating the raw material for third party software - such as with focus shift. The other approach is to incorporate third party software or functionality in the cameras so it can be applied to stills or video.
The Z9 will probably be two years old before a replacement is announced. It most likely will be a modest update but without the groundbreaking changes. Those features and technologies are in trickle down mode now.