Here is my take on Canon and their video DSLR.
If Canon want to do the smart thing they will bet some money on Cinema EOS line. Where I am from the C300 has been hugely popular among production companies and broadcasters.
The main reason I think is that it bridged gap between the DSLR and the large sensor camcorders. If you have worked with a ENG camera, you know how a camera should feel and work, if you want to an effective tool.
We want to use all our Canon glass with a large sensor, but the DSLR hassle can get tiredsome. The answer have been C300 for the most part.
If think Canon have a good chance to cement their position in this market if they make an effort with the Cinema EOS line.
On the other hand, if the 5d Mark IV is a complete game changer, it might turn out different, but I wouldn't get my hopes up just yet. .
The thing is, the market for video DSLRs and the market for the Cinema EOS cameras are not the same market. They never were. A dude may stretch his wallet to get a 5D to shoot some short films, but there was no way that guy was ever going to pony up $15 grand for a C300.
Literally all Canon had to do to own the micro budget marketplace was to take all of the existing components of a 5D and put them into a more video-centric ergonomic body, and throw in the Magic Lantern video features as software. That's it. That's what people have been begging Canon for these last four or five years. They didn't have to create new sensors or even 4k recording, any of that. But they never built it. Instead they came out with cameras that had most of those features but priced $10k above people's reach, so only actual production companies could afford it.
Now, even if Canon did come out with a Cinema 5D tomorrow, it would be too late. The tech has moved way beyond it, way beyond what even the Cinema EOS line is capable of, and for far less money. There isn't a single thing that the 5D or 7DII can do with video that isn't done better by somebody else, for the same price or less.
That's the bottom line.