That expresses it well. After shooting mostly 1D4 for a few months there was a very depressed feeling going back to my 6D but certainly not due to IQ. The FPS vs. higher resolution either/or issue is problematic for a primarily wildlife shooter. 10 FPS was enough for me. And I don't regret not buying the 7DII relative to non-1DX features but would have bought it if it hadn't been for the early adopter's having issues with AF.
While I appreciate the fact that some photographers want a high resolution sensor in a 1D body, I am just not sure if there is a large enough market for Canon to develop that camera.
The 1DX Mark II is already $6000, and a 1DsX will have to be pushing $8000+, and bringing it awfully close to a Pentax 645Z. I don't think enough landscape, portrait or studio photographers really want the build and ruggedness of a 1D level camera, hence the 5Ds. The build quality and responsiveness is still good, but just not 1D-level.
Agree the market may be small, but the technical challenges to offer that product would also be small.
I'm not arguing for a high FPS / high MP rig or a brand new 50 MP sensor that is better than the 5DS. Far from it. I'm asking why Canon isn't taking the current 5DS sensor and integrating it into the 1DX II body and letting it snap away at 5 FPS like it does on a 5DS.
Sensor = 5DS
Framerate = 5DS (5 fps)
Everything else (body design / grip / controls / menus / interface) = 1DX II
And I'm not convinced it necessarily needs to climb in price. A 5 fps rig does not need a 400K actuation rated shutter/mirror setup or as comprehensive of a tracking AF setup.