An 8K camera has to be 40+ megapixels, and customers of 1DX and D6 are *asking* Canon or Nikon to keep it at 20 megapixels.
That's news to me.
In fact I've disregarded the 1DX3 because it didn't deliver a resolution increase over the 2. And for landscapes the old creaky 1Ds3 comes out, still the highest resolution 1D ever ( and the most expensive adjusted for inflation).
The 1D series was never just a sports camera, it was the top-tier-workmanship workhorse that got the job done regardless of weather and abuse. The deal was that canon offered the best, most durable technology they had in exchange for a lot of money.
Canon diluted the proposition with the 1DX, because their technology couldn't deliver high resolution *and* speed. Finally a decade later they might be able to remedy that.