OK ... I missed that one, although not stated to replace G12 .....
For me it ticks some of the key boxes ... 3" screen, 1080p video, RAW
With a 1.5" sensor That is a big increase over my Fuji, (and x 6 bigger than G12) hopefully this keep resolution sharp with the large pixel count.
Wonder if it will have a Canon Housing with a standard round screw thraed port ... or the awful rectanglaur type seen on previous Canon housings.
The lens focal length is OK, but aperture is a little disappointing ... be interesting how the Low Light performance is, key consideration for underwater use.
Be good to see a full test review once out ... only 'first glances' so far - however this one
Canon PowerShot G1 X Preview: 1. Introduction: Digital Photography Review
gives hope that Low light at wide angle (what we need) should not be an issue.