Detailed piece, but you omit the most important question: who is the “third player”? With digital, optics takes a supporting role. Sony appears to have entered, and has some innovations (getting rid of mirrors, i.e. bulk) but the full-frame DSLR market seems right for the taking by Silicon Valley startups.
Also, these two revered old ladies have formed a duopoly in the U.S. Notice how you can’t buy their full-frame models in the big box stores? I wonder what Costco thinks of that.