Originally posted by Rondec I have a feeling that a lot of this is driven by the sensor department. I am not sure how many different sensors Sony is making but it is a lot (12, 20, 24, 36, 42, 61 just for full frame) but when they release a new one, the camera side of things is charged with building a new camera around that sensor.
Canon on the other hand has a tendency to put the same sensor in multiple different bodies and just change the feature sets a little bit. I very much doubt that Canon is going this path at all. Nikon probably will have a couple more MILCs to release in the next year and then will focus more on lenses for the Z mount and shift back to an upper end F mount camera or two.
Sony, Canon, & Panasonic are all heavily invested in video in some way. Sony, Panasonic, & Samsung are also all invested in display panels. If they want people to buy the new 8K displays, then they need people making 8K content so you have to drive both sides of the business.
The 61MP sensor that everyone is getting worked up over has a twin that nobody is talking about. The push for speed and processing power is really what we are seeing and the resolution is part of that. Sony has the IMX521CQR which is also a 61MP sensor except that its a quad Bayer array.
Sony has published the specs for a full-frame Quad Bayer and five other sensors - DIY Photography This will net a 15.xMP FF sensor that will yield much improved DR and probably color accuracy with very little noise at higher ISO. There is a lot more processing needed to bin the pixels like this and more memory on sensor (I assume a stacked sensor). This is going to take a very powerful processor. The 61MP sensor in the A7rIV is basically a bi-product of where Sony is going. Basically, the quad Bayer sensor is taking 4 images with every press of the shutter button and combining them to produce a single 15MP image. 10FPs means the camera has to process 40fps. It's possible that this quad-Bayer sensor shows up in the A7sIII or a new line of Sony E-mount cameras.
Eventually Sony will launch a 132MP FF sensor and the internet will proceed to stroke-out, but that will allow them to capture 8K or 33MPs stills with 4 pixel binning for some pretty amazing DR and very low noise.
It might surprise some of the experts on this board, but Sony does know what they are doing when it comes to sensor production. The may suck at designing menus and ergonomics, but they are currently the industry leaders in sensor technology and there is a reason for that.
People need to stop worrying about how well the A7rIV is going to sell. The A7rIV is a very small piece of the puzzle and a stepping stone on the development path. People seem to think the A7rIV is the end game for Sony and that's pretty naive.