I don't think Canon should enter the Mirrorless market in this way.
EOS mount is what it is. In order for a mirror-less system to make sense and really use the smaller body possibilities, you need completely new lenses/accessories along with the new body style, at which point it doesn't matter what the name is on the camera or what equipment you already own in your existing collections. There already are systems out there that handle this, Pan/Oly > Lumix/micro 4/3rds, etc. on the reasonable price/crop side, and Leica - M series, etc. on the high price/FF side, and those systems have a huge advantage already in lens selection, etc..
Personally, for any sort of new compact style system, I think the best direction(s) for Canon is to pursue pushing the bounds of point and shoot cameras as well as higher end camera gear built into cell phones/technology partnerships. There's money in that, there's interest in that, and the field is wide open. Mirror-less/compact systems photography is a niche and it's already well covered by Leica/Panasonic and others.
Another great direction Canon can persue on EOS is bridging the gap between Full Frame and Medium Format. Much like the partial compatibility between EF and EF-S, they could go the other direction and instead of a smaller sensor, go towards Medium Format sensors, with lenses to match that are compatible with Full Frame as well, possibly even vice versa with a circular image, like an 8mm fisheye on full frame which can be cropped to square/rectangle in post. Right now a transition from entry level EF-S to Full Frame is do-able, but the jump from Full Frame to Medium Format is enormous and as sensor technology is near commonplace architecture it's nigh time to bring Medium Format to a wider market. And this one might be hard to swallow but the idea of an open source camera system, one with interchange-able mounts from any vendor and user programmable functionality, is long over-due. The markets of the future will no longer bear the outmoded, planned obsolescence/proprietary models of yesteryear, better to come to terms with that ahead of time rather then when it's too late.
(very nice 3D designs and renderings/concepts from the designer, very cool)