sunnyVan said:
I'm one of those people who upgraded from 6d to mk3. I upgraded for the extra AF points, not those extra features that are really nice but not a must to have. The 6D matches 5dmk2 in many ways. It's reasonable to expect a 6dmk2 to match 5dmk3 in many ways. And when a 6dmk2 is almost as good as a 5dmk3, it becomes very difficult to justify paying premium for extra features that regular joes don't need.
Back to my point. 6Dmk2, if it exists at all, will be very competent. 5dmk4 must beat it in some very important features.
Sorry, but you've ignored the elephant in the room - cost. The 5DII was launched at $2700, the 5DIII was launched at the
significantly higher price of $3500. When the 5DIII launched, Canon continued (officially) selling the 5DII, which is not their normal practice when launching the next model in the line. They did that because the much higher price of the 5DIII left a gaping hole beneath it. Subsequently (about 6 months after the 5DIII), the 6D was launched and
that was the direct 'replacement' of the 5DII, which was then discontinued.
So, yes – the 6D was similar to the 5DII, but the 5DIII was a major improvement over the 5DII (it got the 1-series AF, unprecedented for Canon). The 5DIV is stacking up to be a relatively incremental update to the 5DIII in most ways, so it's not likely that Canon will deliver major changes in the 6DII. The 6DII will improve on the 6D, but it won't leapfrog up to match the 5DIII.
sunnyVan said:
I see DPAF as a reasonable differentiating factor.
It's reasonable, but I don't think Canon will do it. Frame rate, AF, build and sealing, dual card slots, 4K – that's ample differentiation.