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mirrorless and extreme clarity are what Leica have been doing for decades so they are not innovations
I'd argue against that.
I love Leica, I have a romanticised affection for everything they've ever done.
But if you remove the emotion and look at scientific measurements of sharpness, chromatic aberrations, vignetting, etc... then all of the great lens that currently exist come from the last 10-15 years. That is quite something.
https://www.dxomark.com/Lenses/ has a database of nearly every major lens from the past 50 years (though you have to pay to get access to the totality of their database and they gate Leica and full format things as they know those customers freely spend money and will pay money - but still, all the great lenses are relatively recent which is driven by digital sensors exponentially improving)
Is this the disc brakes are dead of the camera thread?
About the only thing that hasn't yet seen a huge leap is the design of the body itself, but even then there are some unusual body designs emerging for some use-cases (going to pick Sony just because I'm lazy and you can do your own research), i.e. this very weird "mount the sensor to the back of the lens" thing (mostly for remote control rather than hand held use) https://www.sony.co.uk/electronics/interchangeable-lens-cameras/ilce-qx1-body-kit and the cinema line https://www.sony.co.uk/electronics/interchangeable-lens-cameras/ilme-fx30 where the bodies are designed to be similar to an SLR but yet are constructed for silent use, mounting things on them, and have things like indicators to show when the camera is live, etc.
There's an overwhelming amount of innovation happening in cameras. Every part of a camera made today is several generations further on than a camera made a decade ago. Only the body remains familiar with lens mounts remaining the same due to the investment people have made in lenses. But even then... lens have also seen huge improvements as a 60MP sensor will show up the smallest flaws and aberrations in even in the best lenses in the past and so lenses have had to also become near-perfect to survive contact with incredible sensors.
I mean, that's hilarious.