First, XQD is a sony technology. I am skeptical that Canon will ever adopt it.
Full frame DPAF CMOS
7.4 fps (5fps in "silent" continuous)
Same 61pt AF system as 1D-X Mark-II
Same touchscreen LCD as 1D-X Mark-II
8bit DCI 4K, 24/25/30p (Mjpeg)... clean HDMI out
Slot 1: CFast 2.0 ... this offers speed for 4K and good buffer performance
Slot 2: SD (U3/UHS-II) ... this offers cheap high capacity media for jpeg/mRAW/sRAW
I hope CFast is implemented in lower tier models as well. (e.g. 6D mark-II / 80D)
It would be nice if these models include 4K 60p bursts even if just for 1 or 2 seconds. These would be marketable features and the economies of scale (for card manufacturers) can help lower the cost of CFast. If they can forecast higher sales then they can reduce price at least for medium sized cards
There are some pretty good lists floating around. I think we should not forget that there are likely two more FF bodies coming in the next 12-16 months, the 5DIV and 6DII. So not everything needs to be dropped into the 5DIV. I am actually hopeful that the 6DII becomes an enthusiast/prosumer beast.
Canon does a good job of tailoring their cameras to a core market. The 5DIII was wedding/event photographers. I hope that target market does not change, but it might. If that stays the same, I suspect a lot of the above specs are pretty close.
Video (not that I personally care, but many "wedding/event" shooters would):
I wonder if Canon thinks they need 4K or not? I can see 60 fps at 1080p being sufficient.
If 4K, then CFast, if 1080p, CF.
Touchscreen and DPAF---both make sense as nice improvements
The 1DxII has 8-bit, but I wonder if we might see 10 bit video?
1Dx II AF. EV -3 (maybe lower?). I hope to get the f/8 AF at all points, but that might not happen.
I think the flipscreen ends up in the 6DII and not the 5DIV.