don't care for video, don't need or want "global shutter" in a DSLR.
You still get rolling shutter artifacts (skew) when taking pictures of fast moving objects.
Yes. It matters for still... a lot less, because the effect is less obvious in stills, but it does.
Personally, I don't believe the rumor. Canon hasn't "innovated" in the DSLR video space for a while. They've only ever made their video less crappy faster than other manufacturers over time. And I say this as a video guy who currently shoots with a 5D3, and also shot with a 7D and 5D2 when they were the bee's knees in video.
A brief timeline of video on Canon DSLRs:
The 5D2 gave us full frame video for the first time, but no manual audio, no manual exposure, no 24p and 30p wasn't even 29.97 like it should be. It suffered severely from moire, rolling shutter, and bad codec.
The 7D gave us 24p and manual exposure out of the box. It still suffered severely from Moire, rolling shutter, and bad codec.
The 5D2 Eventually got manual exposure, 24p and manual audio, but still suffered from severe moire, rolling shutter, and bad codec. Of course, nothing below the 7D was any better. Eventually, one of the rebels got an articulating screen, which is kind of nice.
Mind you, all these "problems" weren't problems on non-DSLR video cameras, so we're just bringing the cameras back toward "normal" not "good".
Then came the 5D3, which finally got rid of moire, at the cost of overall sharpness (again, I speak from personal experience) and slightly less bad (but still bad) rolling shutter and a slightly less bad (but still bad) recording codec. Worst, 5D3 has hugely ugly fixed pattern noises that were NOT present in either the 5D2 or 7D... progress. Oh, I guess I should give Canon some kudos for enabling clean HDMI out, but they weren't even close to first there, so to say they "innovated" that feature is stretching it a lot.
Around the same time, the 1DC was also announced. Its "innovation" being a 1DX with slightly beefier processors that can shoot cropped 8 megapixel (that's what 4K translates to) JPEGS at 24 frames a second. You could've predicted what the 1DC was going to be from the specs in the "development announcement" just by crunching the pixels processed per second number in the 1DX. I did, and the 1DC was an absolutely no-surprise camera for me.
That's it. That's all the "Innovation" they gave us so far, concerning DSLR video.
Not that the other manufacturers are doing much better, but to believe that all of a sudden, Canon is going to break new ground with not one but TWO features, one of which has only ever been seen in ONE digital cinema camera from a competitor? I don't think so. (By the way, that would be global shutter on CMOS sensor in Sony's F55, and I believe the "cost" of the technology was a half stop less sensitivity)
Would I dearly love Canon to do global shutter and 2.5k in a 1DX-2, 1DC-2, or even a 7D-2? Hell yes. If it comes with a good codec (and I mean 8-bit 4:2:2 in-camera minimum, 10-bit preferred) I would pay 10k for it in a heart beat. The amount of problems global shutter, better codec, and a sensible amount of resolution increase would MORE than justify the cost.