I want:
More DR: it doesn't even have to be 14+, just give me a bit more than every other Canon camera released over the past 5 years.
4k video: H.265 would be nice...there's already a Samsung mirroless cam with this capability
RAW 1080p @ 60fps: or at least a VASTLY better compressed 1080p codec, make it look as good as the jpeg's
Dual Pixel AF: would be so great for video focusing!
What we'll get:
Better high ISO jpeg performance, marginally better high ISO RAW performance
1fps shooting speed increase
An extra button or two
Strobing light correction
built-in intervolometer (FINALLY)
"IV" badge
I actually think that the new 5D might get Dual-Pixel AF...about 50/50 chance. Just trying not to get my precious little hopes up. :'(