Since my EOS 1000n I've had PIC modes, and Canon have yet to make me a sports photographer, portrait photographer or firework photographer, in much the same way that not everybody with a video enabled DSLR will a) use it at all for video b) get beyond the basics. In fact, we could probably assume as much about the majority of EOS cameras sold with an A mode.
I have yet to handle a 70D so can't comment on how good or bad the new live view AF system is.
What I can say with absolute certainty is that I won't use the new AF for video it no matter how good it is.
Here is the basic problem with video AF:
Stills AF has to have the subject in focus at a single moment. If you shoot a burst with tracking AF and have a 50% keeper rate, you throw the others away. Simple.
Folk see your pics and comment about the sharpness and you feel really chuffed with how well you can set up your camera. This sounds facetious, it isn't meant to be, I do this when I've my stills hat on. I feel a pang of pride, in that my Ai-Servo response tweaking has been a success. I'm delighted with my judgement to set the af limiter, and my use of the cross rather than the point or the zone. Yes I had to climb the hill, be at the event early to get the best spot, to be there, but I'm only kidding myself if I think anything other than that the camera did 90% of the work. With regards to focus at least. Look yourself in the mirror and try and tell yourself anything different.
So what's my point? Video isn't like that. You can't chuck away the bits the AF missed. Video is contiguous. And every frame has the potential to reveal your ineptitiude. Yeah you can cut, and do mis-en-scene or montage or whatever other film-makers trick, but for the clips you use, you need to be in focus.
A couple of scenarios... you are shooting a horse & rider, they are charging straight towards your very long lens with very shallow depth of field. What do you focus on and track? The jockey? The horse, the tv car behind the horse, the steward thats just stepped out in front of your camera partly obscuring the horse and rider? For stills no problem, your Ai-Servo beahaviour is set to temporarily ignore subjects that are much closer than expected, so by the time your steward is out of shot the predictive tracking has done it's job and you pick up where you left off. AF video? No no, not a go. Backwards, forwards, damn damn damn. Everybody see's it on your 50 inch plasma... writ large...
There has been video AF around as long as I have been doing video, as a school kid, as a hobby and as a job, and there are only two AF innovations that I regard to be anywhere near useful.
One-touch AF. Great in a hurry to get a quick pick up shot or to get close enough to FTM adjust.
Focus directon on the Sony VX1000. A great idea, arrows show you in the viewfinder which way it thinks you should turn the lens to attain focus. Not blindly relying on AF, not totally relying on your own MF skill, this was a great system, worked well enough with 1/3 chip cameras, don't know how good it would be with APS-C or even full frame.
Another difference. In stills you can choose your AF point and move your camera around to track your subject.
In video, you cannot, the footage would be horrible to watch. So you need a fairly static frame, or the moving subject has to be fairly evenly positioned within a fairly static frame of a moving camera.
The only way to do this is to manually focus. Now there are lots of tricks you can use in video, especially if you have servo zoom parfocal lenses (you start off close where focus is critical and slow zoom out to where you can be much less accurate to account for bumps etc), zone focusing (something of a lost art) and you need the best lenses to do this, that don't breathe, that have end stops, that all turn the same way with even dampening etc.
The STM lenses may well do a smooth job, but the ones I've seen so far have terrible narrow short throw focus rings. Not tactile. Not smooth.
Finally. You know at a kids party, which of the kids you are recording. The camera doesn't. It's thinking in edges, in contrast, in whats closest to the camera. If you can get a decent long throw fast aperture lens then with a bit of practise it is fairly easy to track and micro-adjust focus on the fly.
Canon may make video available to all, but not all are going to like it (i cannot do stills and video on the same job, despite using the same camera, lens tripod etc, my head is thinking completely differently.
And this is before we get to audio.
Video AF might be fine for family stuff, but for serious video use I don't think it will ever get there. The camera might be quicker once a decision is made, but we are smarter.
Photodesks will use anything these days. Aspiring photojournalists? Aspire no more. Just be happy with a credit, a very modest fee if any and find a day job to pay the bills that doesn't make you too suicidal.
Aspiring videographers. It's a different ball game. A fancy new AF mode is not going to make any photographer a videographer. There's a bit more to it than that.
I love photography, I am in awe of great photographers because I am aware of my limitations. When it gets to the good amateur level, like club competition winner level, features in AP magazine etc, I don't want to put you guys down, but to attain the same level of competancy with video, you need to be good all the time, you don't have the same scope to fix things in post (for example, video sharpening looks horrible) you need to be on the ball with your white balance, you need to be able to look at a scene and decide on the best wb setting, or which gel combinations to use on what source to even things out. You need to understand how to place a mic so as not cast a shadow. You need to know what the line is, and what side of it to be on.
I guess my basic point is this... point and shoot video is going to be no better than point and shoot photography. Occassionaly you might strike gold. Usually you'll be in PS or LR doing a bit of work. Yes in video you make cuts and chuck stuff away, like in stills. The big difference, and that which video AF is yet to overcome, is to be smooth, always, at 25fps. And the only way to do that in video, it is my sincere belief, is to take control, particularly of focus.
Sorry for the essay, but you wanted a reaction.