@Retzius
What they know (and what you fail to notice) is that there will always be a demand for robust, straightforward cameras. So this is a safe bet, although it makes it impossible to keep the revenue they had a while back. These cameras can evolve much slower than the most “innovative” ones, because “being innovative” is not why people buy them anyway.
On the other hand, many people who switched to mirrorless, did it because of the size difference. And these people might eventually move to even smaller cameras, when their IQ becomes acceptable. By even smaller I mean e.g. smartphone-attached modules (Olympus Air, Sony QX), because that seems like the most probable future.
So if you forget about the mirror and divide cameras into Large and Small, the Large ones are the safer long-term business, if you want to keep making traditional cameras.
For Sony this is not a problem. They can always switch to QX-styled bodies or revive SLT-like form factor.
Or concentrate on TVs. Or farming.
Started out doing photography at the age of 6 using an uncle's old 1940 kodak brownie box camera. At 15 years of age, I decided to buy my very own 1975 Praktica SLR camera. I now shoot with a Nikon D850. I do unpaid TFP and commercial paid work.