I had an interesting experience working with a photo neophyte. After seeing my good results carrying my Olympus Pen camera in China, she was interested in buying it second-hand. After borrowing it, she was frustrated that she couldn't get good pictures of her daughter's school play or gymnastics or anything for that matter. She wondered outloud..."do I need to get one of those big honkin' DSLRs to catch those shots." ...I had to talk her back away from the edge. I explained that unless she wanted to engage in some substantial photo-education she wouldn't get much better results from the DSLRs either. What I learned from her response is that to the mass-market, these smaller mirrorless cameras bring with them the baggage of inferiority from the digicams because they share the form factor. In the end, smaller form factors with larger sensors may remain the only the purview of the enthusiast because they are the only ones able to appreciate and work with their strengths and weaknesses.
As for my other responses to the canon mirrorless camera. I don't like that it only has two lenses that are sized right. I can't imagine putting my 24-105 on that body and actually using it. Of course, that is pretty absurd. How about my 100-400. Nope, that would not be a practical rig either. The compatibility with EF and EF-S lenses is mostly just a novelty. Some folks may use them in a pinch, but not for regular toting around.
The manufacturers that, to me, have a leg-up in this middle-ground mirrorless camera (between up and coming camera phones and full frame DSLRs) need to have a good collection of matched compact lenses. MFT has that, and they seem to be getting better on their sensor technology. Panasonic and Olympus could find themselves a niche between the down-market moves of full frame and the up-market moves of camera phones. Sony seems to also have a decent play here, but their lenses are still pretty big. They miniaturized the body, but not the glass.
So, mini-DSLRs without the lens have the liability of an inferiority complex gotten from digicams, and the liability of big lenses from their DSLR brethren.
I can't imagine the ergonomics of this little wonder will be anything other than abysmal. Touch screens are not great for making pictures.