it´s all nice and true what you say but i know more people with a medium format camera then with a 15000$ video camera + 43000$ lenses (like the canon CN-E 14.5-60mm).That's because most of the people working in that realm rent rather than buy. They factor that into their prices. You'd have to know someone with a production suite to know someone who owns the C300 or RED cameras personally. This is especially true because a normal video production involves multiple people and a lot more money; whereas someone in photography can, theoretically, do their work on their own.
I just don't get the excitement for Canon medium format. It probably can't use your existing EF lenses, so, you are already not forced into a specific system. And I can't imagine it not being $10k+, as the Canon niche products have come out as expensive, if not more expensive than their counterparts (the C300 is way overpriced, the 1D-C costs 50% more than Sony's F700, and the C500 is comparable in price with a RED system). So if you're willing to spend $10k+ on a MF system, why not do it already with the options that exist?
And again, the Canon Cine stuff was announced in April; yet doesn't exist right now. You can't pre-order it, and even the pricing wasn't definitive at the time of the announcement. There's not even a release date for them to push back 3 months. So you might see this thing in 2013, but at the same price as what exists today...