If Canon put a fixed lens on it and called it a Mirrorless Camera, it would fit in with many of the others. Personally, I prefer the zoom lens.
And that's the only problem; if you use a large sensor, you are stuck with either a fast prime, a slow zoom, or a massive lens (compared to the size of the camera). For example, the Fuji X100 is great if you want a 35mm (equivalent) prime, if not it is worthless. The whole point of interchangeable lenses on most 'mirrorless' (a poor name, if you ask me!) cameras, is that you can choose which of the lens options you wish to own, or to carry for a day's shooting.
I don't own one of these cameras yet, partly because I have been waiting to see what Canon would bring to the party. I like the idea of them because they are light enough to take with you when you're not planning a shoot, but want to have a camera with you in case the opportunity arises. I'd rather have a 'coat pocket' size camera with DSLR image quality than a 'shirt pocket' size camera where I would always wish that I'd have had my DSLR with me.
I also think that these cameras would be great for street photography -shooting from waist level with a tilting screen, where a large DSLR camera with an eye level viewfinder makes you stand out.
In summary, a "Super G" would be great if it had an APS-C sensor with a 24-105mm (equivalent) f/2-2.8 zoom and was no bigger than the current G12, but the laws of physics are probably against this; so interchangeable lenses are the next best thing.