Signed up to put in my two cents on the wish list. In order of priority:
Significantly better DR by say...at least 1.5 stops.
Very clean images at high ISO's. Perhaps 4 stops better than we have with the 5dII.
Slightly more resolution, but not at the expense of the previous high ISO performance or DR requirements.
I would pay much more than a paid for my II to get it, and I'm sure I'd have to.
Ah yes, a kindred spirit. First, four stops improvement at high ISO may be a bit too optimistic. I'd settle for something as good as the Nikon D3s. I think one stop improvement over that camera may be possible. As for dynamic range improvements, I'll take as much as I can get.
Second, regarding resolution, would you accept slightly lower resolution, perhaps to 16.9MP, if it got you dramatic improvements in high ISO image quality? That is one rumor that circulated at the beginning of this year.
Third, after reading this: http://www.lensrentals.com/blog/2011/06/photo-lenses-for-video-there-is-no-free-lunch I'm not sure how much I want video in my DSLR.
Fourth, given how good the 5D2 and D700 are and how old they both are, you may not have to pay more.
Fifth, I don't think it'll be called a 5DMk3. I think that name will be reserved for a 35-40MP studio/landscape camera.
17MP vs 21MP is not going to give you a dramatic improvement for high ISO, it would be a barely even detectable difference and the low ISO DR might go DOWN by even slightly more.
But anyway I'd rather it be 24-27MP and 6.3fps than 35-40MP and 4fps.