Looks like a nice camera from Canon but it just seems like Canon has their customers locked in with a lot of investment in Canon glass.
Really looking at this it's a jack of all trades $3500 camera and it is just too high in the age where Nikon has a D810 for $700 less, Sony has a mirrorless A7R2 beast for $300 less and little old Pentax actually has a full frame camera which does some things better(better sensor, higher shutter life, better weather sealing, rear pop out LCD screen, pixel shift resolution mode, external LED lighting for nighttime, In-Body image stabilization..etc) than the Mark 4 for literally half the price.
Don't get me wrong the 5D4 looks like a cool camera but when you look at the price, the competition and the fact this camera is probably going to be the placeholder until their next update for the 5D5 in probably 2020 then it starts to seem a bit disappointing. I can't blame Canon. They have it priced to get a slew of guaranteed early adopters to pay the hefty sum to help recoup r&d.