There are so many good camearas available now, it looks like cameras for professional photography will be dirt cheap by 2020. I'm making the estimate based off the fact that thousands of photographers made images that wowed clients, using the likes of Canon 5D mk ii, Nikon D700 and other bodies. Good images were taken, photographers claimed they were "professionals" using cameras deemed old now, and many clients were satisfied. So with current cameras as good and better, and new models coming out, it seems that by 2020, photographers could use any new or used models dating 2008 to 2016 and still take great photos. And they should be able to find such cameras for $800 to $1500. I consider that as fairly "cheap" or inexpensive to crank out very nice photos. Not knocking $3000 or $6000 cameras. But it crossed my mind today that today's cameras are damn good, and will still be damn good 4 years down the road or 8 years down the road after their price value drops like a brick. This probably won't dictate the best bodies I upgrade to. But seems promising for for backup option costs.
On another note, it's unimaginable that Canon would never release a pro grade mirrorless. So I can only imagine what each manufacturer will be producing for options and technology 12 years from now. For those who can afford new gear and make income, it's certain that for plenty of them, that technology streamlines their workload enough to compensate much of the extra cost.