Let's not forget that mirrorless digital consumer cameras have been around for way longer than DSLRs - if you look at all digital cameras and don't fixate on those that have fixed lenses vs those that have removable lenses. Mirrorless isn't a technology that's developed over the last ten years. It's a technology that's developed over the last 25 years or so
My first camera was a fullframe mirrorless. In 1970s.
While the DSLR has taken over the entire market for SLR cameras, mirrorless cameras of all kinds have overtaken them and outsell by several orders of magnitude simply because they can now be reduced in size to the point they fit inside a cellphone.
Mirrorless cameras were always outselling SLRs.
The average person no longer needs a camera.
The average person already has a camera. And that camera is mirrorless. What the average person does not need (and never needed) is an ILC.
And now the DSLR is stuck. Without a full live reading of the digital sensor for the camera CPU to interpret the DSLR has to do its best from the limited view of the image it gets from the low resolution PDAF sensor behind the mirror. It's quite incredible how far they've pushed this technology and how well and how fast a modern DSLR such as the 5D Mark IV can focus,
The main advantage of an electronic SLR is a moving semi-transparent mirror that allows it to use
three different sensors to prepare and capture the same image. For the modern camera, it's a 3d-information sensor at the bottom of mirrorbox, fast 2d color exposure and object tracking sensor above the mirrorbox, and the final image sensor behind the mirrorbox.
If you think that the two specialized fast sensors are not good enough for you because of their "low" resolution (which is still too high for the contemporary image-processing neural networks to run at full fps on embedded chips), you can turn them off by locking the mirror up, which will conveniently convert your camera into "mirrorless".
but the DSLR is hindered. It can't do proper eye autofocus, realtime histograms, focus peaking and all the other things that we take for granted with the modern generation of mirrorless cameras.
They can do that - and more. It is just not the market segment they are optimized for. When you really need fast autofocus acquisition (and not just tracking), you have neither time nor screen space for focus peaking and realtime histograms. You still may need to grasp what is in focus and what is in the dynamic range, but your brain should be pretty capable of doing it over OVF image.
When people realise their phone camera has a more intelligent focus and tracking system than their $3000 DSLR they start to wonder if they made a mistake.
...except that it doesn't.
And if it does, it burns the phone battery in no time.
Now, I'm sure many of you will start saying that your DSLR is perfectly capable of taking the photos that you want to take today - and that's true. And that's why I also still use a DSLR.
My phone is perfectly capable of taking the majority of pictures I need. My PowerShot is perfectly capable of taking the majority of the rest.
I'm not saying the DSLR is useless. I'm simply stating the economic case for why camera companies will inevitably drop them.
I am not saying the market for DSLRs won't shrink (or even disappear). I'm simply stating that there is no reason to believe that FF MILCs will do any better.