Well here goes. This is my first post to this site but I have been a regular rumor reader for about a year now. I have some of my own ideals about Canon’s plans that I hope will maybe bring new life to the near dead 5dmklll rumor horse.
First I think that canon has no intentions of weather sealing the 5dmklll.
I also don't see it having 30+ mega pixels (nor the d800 for that matter).
No eye following auto focus but just maybe the 7d's amount of focus points and viewfinder LCD will make it. In fact I'm almost sure they will despite rumors saying otherwise.
5fps sounds about right to me and probably some improved video capability but I don't know enough about dslr video to even know what they could improve other than having a dedicated switch to change between video and stills.
I can't see Canon putting weather sealing in a full frame camera that needs to be as "cheap" as the 5d needs to be unless Nikon does it and they won't either, so your only hope for a low priced, full frame, and weather sealed camera is Sony (they have the sensor and no pro-body market to cannibalize). As far as the auto focus, I think the new 1d's system is probably far beyond the 7d's which frees the 7d system for use in the 5d. I know allot of current 5dll owners an even 5d owners who never upgraded will buy a 5dlll if it gets that auto focus and viewfinder LCD. I also know that people waiting for the 5dlll to be announced so they can get a used 5dll cheap will splurge on the new body instead for that auto focus, especially, if they currently own a 7d (you know a luxury once sampled bla bla bla) and Canon has to know this also.
If Canon does make a normal bodied, full frame, and weather sealed camera for photographers who want the durability of a 1d with the size and weight of the 5d, it will be a new line without the baggage of an existing market to alienate with the resulting high price tag. That mythical beast would get the updated eye follow focus and probably a price tag only slightly below the 1d cameras if not equal in price. It would probably take a hit in battery power as it would use a weaker battery to fit in the smaller body. It may be a reincarnation of the EOS 3 called 3d (but they might call it 1d lite or something stupid like that). I'm going off on a tangent but I think you get the point.