I think this guy sums up in one video all the things we have been discussing on why camera sales have declined.
https://www.youtube.com/watch?v=vu1UagrnW4g
I found it interesting that he has two friends who are top notch professionals in Malaysia and are still using older DSLR's. The Nikon D700 and the Canon 5D Mark11. Why? Because, he says, they are good enough to produce outstanding results. Of course he outlines many other reasons including the rise of social media and the smartphone. Well worth a look. He also makes interesting statements about photography as art, even we don't agree with his views.
JR
I didn't get through all of Robin Wong's video yet, but I agree strongly with his talk of "camera sufficiency", and I would say even more specifically "sensor sufficiency", even for the great majority of professional photographers. (At ease Doug Peterson; I am talking here about "most" or "the great majority", not "all"! I know that some people want to count the pores and tiny flecks of make-up of on the faces of the underwear models on those bus-stop ads!)
On the other side of the equation, it seems to me that the IQ and camera performance needs of even a large proportion of professional photographers have not increased much since the film era. The one viewing situation I see much of where images get viewed "larger" than with film, and thus need to sustain closer scrutiny, is on computer screens and big-screen TVs, now reaching 4K or even 5K — and that is still in the realm of almost every recent ILC, at least from 20MP up.
(Do any actual professional photographers care to comment?!)
Balance that with the fact that sensor IQ from almost any recent ILC easily surpasses 35mm film and is into medium format territory (by my reckoning, the 56mm frame width of color roll film is good for about 5K to 6K across, so in the realm of 20-24MP sensors), and we have reached the point where even modestly priced recent ILCs,
when paired with good enough lenses, can handle a large proportion of professional work, including a chunk of what needed medium format film rather than 35mm.
Maybe that means we are headed for the far slower update cadence of film cameras, or even slower: remember the gentle rate at which Nikon's high-end AF SLRs advanced from F4 to F5 to F6? And remember when many amateur SLR owners basically bought one for a lifetime, or replaced it only when it broke down after several decades?
One little bright spot for camera makers: electronic devices like digital cameras are unlikely to have the lifetime durability of a basic film-eating SLR. For one thing, the memory cards for my first few digital cameras are now obsolete!