I think that gets at one of the central issues of the mirrorless concept: what is the sensor size? Larger sensors deliver better IQ. Physics is physics -- you can't get a FF photo with shallow DOF without a FF sensor. People love the portability of some of the systems but their sensors are tiny. The NEX does look funky with large lenses and a small body, and that is APS-C. Larger sensors need larger lenses, and larger lenses are not as portable. And if it's not as portable, does it have much advantage for a traditional SLR setup for the general population?
Canon already has the full frame and a APS-C format. Does it really need a third like Nikon? And if it is APS-C like Sony, does it gain you that much if you're hauling EF and EF-S lenses around anyway? Just think of how many threads will be "I'm tring to decide between a mirrorless, APS-C and a FF -- PLEASE HELP!!!" and "No, you much buy the FF (L) lens so that it can be used your your mirrorless now, your crop body in the future, and the FF in the distant future!"
The holy grail is something that is small and has amazing FL range, large apertures for low light capability, ultrahigh ISOs and has a AF system responsive enough for sports action. Current optical and sensor technologies can not meet that. Getting rid of the mirror will not meet that. All systems are a trade between IQ and portability. The first company that solves this problem will win the market... but I'm not holding my breath.