I'm not going to bash on people who may or may not own a Canon. Whatever. This is a forum. We come here to discuss.
That being said, I have to question those people who constantly go on and on about dynamic range. Particularly the people who say that the 5Ds will not even make a good landscape camera because of the decreased dynamic range in comparison to the D810 and A7R. Have these people actually done landscape work? I'm not talking here and there. I'm talking on a consistent basis. I have. I still use a 5D2 because the 3 wasn't a big enough jump in resolution. That's a 7 year old camera. I have also used my friend's D810 and 14-24 which he was kind enough to lend me for a recent week trip down the OR/CA coast and another week in the Sierras. It is true the Nikon packs more DR. However, this increased DR is rarely as useful as some people would have you believe.
During the daytime, there's no difference in general. The one time where there was an advantage to the Nikon vs Canon was in a rather dense forest during a cloudless day. In general, the forest was dark, but of course sunlight peaked in through the trees and leaves. These were pretty bright hotspots. In post, the Nikon handled it better than the Canon, and looked much closer to what my eyes saw one I raised the shadows. That being said, it's still a daytime picture, with sun, in a dense forest. It's very hard to make such a scene look great, no matter how much DR you have. Some things just don't translate well onto camera.
During sunset/sunrise, there was no situation where the camera really made a difference. A lot of times, the Canon could deal with the dynamic range. As bad as everyone says it is, it still can be pushed a bit in the shadows, just not as much as the Nikon. Typically though, the Canon camera can handle the scenes. There are certain scenes which it can't. I'm talking about facing towards the sunset, as the sun sets behind a mountain. These are scenes were you have intensely bright sky, combined with the dark backside of a mountain receiving no direct light. In these situations, even the Nikon couldn't get it right, and I had to bracket (actually I just take 2, never found a need for 3 separate exposures). Another situation I came upon that the Canon couldn't handle was at the ocean. There was a setting sun. There was also a hole in the rocks near the ocean, with water at the bottom, obviously a product of the powerful erosion forces. Needless to say, this was a dark hole (whatever you want to call it), with no direct light hitting it. Guess what? The Nikon needed to be bracketed also.
I'm not saying there's no situations where the Canon won't be able to get a proper picture but the Nikon will. Those situations do exist. But they're quite a lot more rare than some of these DR-fanatics believe, or perhaps they simply lack the skill in post processing. But even in those situations, we can still just take a second exposure to account for the lack of light. Even on the Nikon, in many cases, I took two pictures, because a properly exposed photo of a dark area is still leagues better than simply raising the shadows.
This is all to say, in my 9 years of being a landscape photographer, I have not once come across a scene that I couldn't photograph due to dynamic range. Sometimes I have to take a second shot. This is pretty much a non-issue though. Click the shutter again. The fanatics on the forum always come up with some hypothetical situation where multiple exposures would not work, such as the wind blowing fiercely on brightly lit trees with a dark unlit mountain in the background, or any other multitudes of ideas (and I've heard a lot), but in real world practice, this has never came up as an issue. There's always a workaround, and it has always been easy. Usually, it's just snapping another photo at an increased duration.
That said, I welcome any improvements to DR. They won't change anything drastically, but it also won't hurt any. However, as a landscape photographer, what I *am* buying this upcoming camera for is the massive increase in resolution. *That* is not as easy to account for as DR. Of course, I can do stitches. But that is more tedious in both set up and in post processing than simply accounting for DR.