Okay, I know one is discontinued and the other is non-existent, but this is mostly for fun and a bit of learning.
Do the experts here think that the overall image quality of the 7DII will match or at least come close to the APS-H 1D IV? Why or why not?
I think it would have to be equal to or better. There has been a huge leap in ISO usability from the 1d4/5d2 generation to their respective replacements. While it seems you only have gained 1 stop or 2 in regards to noise, I really think that the cleanness of the images across all ISO levels have dramatically improved. The noise we are left with is more of a luminance noise, which is much easier to clean up and retain detail. "Tough" noise was my complaint with the 7d. If they ever come out with a replacement, it doesn't need to revolutionize the high ISO game, but just give easier to work with noise at that ISO 800 - 6400level. Id love to see a 16mp "c" sensor that comes close to a 5d3. I would also welcome the new AF systems. If they address these categories (if they ever so release a mark ii) then I would buy one.