If it has a flippy screen and better video than the G12, I'll happily pay $600 for it and replace my G11.
If no flippy screen, NO SALE. (The leaked photo doesn't look look promising.) I'll sooner buy a used G12 on eBay.
I for one have been eagerly anticipating the G15 and all the rumours have been just that, unsubstantiated rumours, we have had nothing concrete so far only speculation. Perhaps's, maybe's educated guesses but nothing concrete so there's no guarantee the 'leaked' image is accurate.
That the single image doesn't show any evidence of a swivel screen doesn't mean there's no swivel screen only that the previous swivel screen had an external hinge bump. If I hold my G11 at the same angle there's a distinct hinge bump whereas the image of the G15, if an accurate representation shows a smooth side. So there are three possibilites,
1) the G15 doesn't have a swivel screen anymore,
2) the image is an artist's impression of what the G15 might look like and not an accurate representation of what the camera will look like when announced (wont be the first time, look how many artists impressions there have been of iPhones over the years which bore little resemblance to the finished article),
3) that the G15 has been completely redesigned of which the repositioning of the viewfinder, pop up flash and loss of dials, bears witness and just maybe Canon have integrated the swivel screen better into the body. Apple did it on their MacBookAirs.
However if when announced tomorrow the swivel screen has gone, so will I have, to the other camp and Nikon P7700 will get my vote and my money despite not having a viewfinder.
If we are wrong in our observations and interpretations of a leaked image are wrong and the screen is still there the G15 will get my vote and my money. We have to wait and see wont we.