The rumor mill is heating up about the "new" canon mirrorless system that is supposed to debut at Photokina. Shouldn't be too hard to put an interchangeable lens mount on
the G11 - it has the size and durability to handle the lens, upgrade to an aps-c sized chip, and there must be some room in there to replace the autofocus chip and control circuitry to accomodate EF lens for a NEX/Pen/G sytsem competitor.
On the other hand, why not take the leap and redo the mount, move IS into the body (a-la pentax), introduce a whole new lens family and start a new market. You could even run a two tier lens line - a mini "L" and a consumer offering. The high end could attempt to compete at the Leica M level and the less expensive line could go head to head with the Olympus/Panasonic and perhaps Nikon systems.
I'd look for a (35mm equivalent) 24mm f2.0 prime, 28-90 zoom, 70-250 zoom and a short telephoto prime (75mm?).