Other than video, and assuming no significant increases in DR or high ISO performance, what is the compelling reason to upgrade from the 5D3?
If we assume these specs are correct, this looks like a small incremental upgrade to me.
Comments?
It sounds like you haven't been paying attention to recent Canon developments in other market segments. The 1DX2 has an all new sensor with improved DR. So does the 80D. The 5D4 sensor will surely have similar architecture.
Other than that, 30mp will be a moderate but decent improvement over 22mp, and 8 or 10fps will be welcome. The robust and well damped mirror/shutter from the 7D2 will be a nice improvement. The AF advances of recent years will be there. If it has a hybrid O/EVF, that will be cool, but not a game changer. Video will be significantly better but I don't care and I don't think you do either. WiFi would be nice.
So , if the DR isn't much better, it may only be an incremental update. However I think there are two things that could make the 5D4 a quantum leap - 1, if it matches or leapfrogs the D810 for DR, and 2, if it has no AA filter.
You mention the 1dx2's new sensor and improved DR.... but 13.5 is still less than the Sony A7 variations at 14, and they're all still below the Nikon's 14.4.
At 30mp, it's less than the Nikons at 36mp, and far below A7r2 at 42mp.
Given these cameras all cost the same, why would your general consumer at Best Buy pass over a 42mp or 36mp camera and opt for just 30mp?
The Canon specs as rumored are laughable when lined up against Nikons and Sonys today. This "flagship" 30mp camera will be a joke in 4 years after another Nikon/Sony refresh... when say they hit 50mp.
Leaf shutters, fast sync speeds, built-in ND or polarizes, built in RF flash control ... those are things that no other DSLR has.