Well,
The new Canon sensor technology is better for ISO, even if it doesn't have a higher ISO. This is comparatively speaking given the pixel density and sensor size. In theory, this technology with a lower pixel density should yield some very high ISO capability.
It isn't unreasonable to think that DR has also improved. Maybe Canon didn't mention it because it isn't a huge increase? Canon tends not to mention something unless it is comparable or better than the competition. That is why they initially ignored the FPS for crop mode. It's not any better.
Some on this forum have said that a sensor cannot be "tuned" to favor higher DR at the expense of ISO. Not sure how true that is. Because there is the sensitivity of the sensor, and then there is the amplification of the information it receives.
If the DR is one EV better, that is a good thing! But it won't be what Nikon/Sony has, and thus not a marketing talking point.
Just have to wait and see the tests....
On the sub-topic of DR in this thread:
Overall, the 5DS will be a success. Pros don't sit there and obsess over DR every day on web-forums. They get out and shoot, because they know that 99.9999% of their shots are within what the camera can do well.
"Dynamic Range Syndrome" is something that afflicts those who have no photographic technique and radically under or over exposes photos because they keep reading that unless they're on manual mode 100% of the time, they're just newbs. Spinning the dial to "M" = Insta Pro.
Yes, having high DR and lifting shadows and other stuff does have a legitimate use by skilled photographers. But I will say this - at least 9/10 users out there are using it as a crutch for their bad technique or lack of technique. That is the cold hard truth whether or not people want to hear it. What these people never understand is, while they can "save" photos - these never have the truly deep, striking, high IQ look that real pros produce. It isn't hard to understand why - sensors do best when fed the proper amount of light. For this reason, they do save photos, but they are mediocre at best. It is these types of users that flood the internet forums with their incessant dynamic range talk.