This is completely missing the point of the thread. The point is regarding the distinction between the 'general-purpose' bodies (D850, A7r3) which shoot everything and the high-resolution/high-IQ/low-ISO specialist bodies (previously 5Ds, D800, A7r, A7r2, D3x, but none in this generation yet). You can put the same lens onto either body, so the lens lineup is not a point of distinction between the two classes of camera.[/font][/size]
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Not to sure general purpose bodies shoot everything, they might shoot it but the ? Is how well?[/font][/size]
I kinda have similar thoughts to Bernard, plus the image acquiring products today for top top IQ are less important for advertising since low res homemade images and video is more accepted actually preferred by by internet shoppers.[/font][/size]
Yet, medium-format bodies exist. Pixel shift exists. People shoot panoramas and blend exposures. There is clearly a demand for better image quality (which includes, but isn't limited to, higher resolution - there are many ways to increase the output data other than just increasing the size of the two-dimensional matrix it's stored in).
Obviously, this demand isn't as great as for more general-purpose bodies, just as the demand for 15/20fps bodies isn't as great as the demand for general-purpose bodies. The D5 and A9 are never going to sell as well as the D850 and A7r3. This is why the 5D3 and D750 did so well (and I'd expect the D850 and A7r3 to do the same, even more so than the D810 and A7r2). But they are still in demand, as were the D810 and A7r2 (when they were the slow, high-resolution bodies of their time).
Despite general-purpose cameras shooting at 10fps and being able to hold just as capable an AF system, the action camera isn't going away - the dedicated action stills camera is likely to disappear as a separate entity, but, rather than dying out, is really just merging with the camcorder as a single device able to fulfil both roles (as a hand-portable camera capable of at least 39MP and 25fps - already, we have 6k video cameras shooting 19MP/25fps, which isn't too different from the A9's 24MP/20fps). The 'middle ground' covered by general-purpose cameras is getting wider, becoming capable of filling more roles that would once have required a specialist action body.
But what about the high-resolution camera (probably now better described as a 'high detail' camera, since resolution is not the only way, and probably not even the main way, it would set itself apart from the general-purpose cameras)? Given the different ways people go to now to increase captured detail, even with 42/45/50MP cameras, they certainly seem unlikely to disappear either.
With general-purpose bodies taking up more of the middle ground, I can see these bodies evolving to become more specialised, geared towards maximal image quality rather than compromising aspects of their design for general use. They would likely go after the medium-format market, encroaching further and further on medium-format IQ (with a 100MP sensor, a sufficiently-sharp lens, and microlenses, filters and electronics geared towards maximal image quality, there's no physical reason a future 35mm camera can't match an IQ3 100MP digital back in terms of output quality), while retaining the 35mm advantages of lens selection, portability, price and commonality of AF systems with their more action-oriented counterparts. They would be able to do this because the general-purpose bodies already exist to cover situations where such sensors wouldn't be suitable (higher ISOs or frame rates). Essentially, they'd have one foot in each area, specialising in low-ISO image quality, while having the AF and other systems needed to back up a general-purpose system (and take the occasional 100MP action shot) when necessary, albeit with a lower frame rate.
Lenses aren't a distinguishing factor between fast, medium and slow cameras - you can put a super-sharp lens onto any of them, and they all benefit. They play a very important role in ensuring that camera systems continue to improve, but don't, by themselves, distinguish between various classes of camera body.
Medium format isn't sacrosanct. Remember large-format film cameras? We don't see too many of those any more, since medium-format digital now outresolves 8x10" colour film. Nor do we see too much demand for large-format digital, likely for a variety of reasons - they'd probably cost hundreds of thousands of dollars (more for commercial reasons than due to manufacturing costs), would be heavy and cumbersome to carry around, and, likely most of all, once you can match 8x10 film, you probably don't need all that much more detail (when you do, you're probably shooting something you can stitch, or are designing a billion-dollar spy satellite). We also don't see too many medium-format film cameras around, apart from the panoramic formats. These were once the staple press cameras, but full-frame digital now outresolves medium-format colour film and is far more portable. (Current resolution-focused full-frame cameras definitely beat 6x9-format colour film and probably come close to 4x5 colour film in terms of detail resolved, and obviously do much better in terms of ISO and DR, when using lenses that can keep up). With sufficient development of 35mm-format, detail-oriented cameras and sufficiently-sharp lenses (easier to make a sharp 35mm-format lens than an equally-sharp medium-format lens), there's no reason that medium-format digital won't itself largely become a relic, used by few other than well-heeled landscape photographers wanting something even bigger and better.
As for web output, the definition of 'web-sized' is changing fast. 4k monitors are now common. You can easily get 6k monitors. 8k monitors have now started to come out. Even the Samsung Galaxy S8 uses 2960x1440 resolution. For ideal screen output, the input needs to either come from a source with significantly higher resolution, or with true RGB values for each pixel (e.g. 6k input for 4k output) - and that's not even counting the cropping and panning of images commonly used for electronic output. The drone cameras and GoPros of the future won't be the present-day, low-resolution cameras using cheap, fixed plastic lenses. They will be 8k-capable video cameras, likely using deformable lenses with a wide zoom range. And, with production and use of imaging sensors exploding globally (they're used in far more things than just cameras), they won't be any more expensive than current drones and wearable action cameras. Yes, they'll produce 'web output'. But the 'web output' they need to produce will be very different from current-day, 700x400px Jpegs.