Maybe the case, but from what we have seen so far, neither the G15 or S110 look exciting as the RX100.
Why isn't Canon offering more with a larger sensor? Though that is only part of it. If they haven't corrected the performance seen recently in the G1X, S100, and G12, then no spec will make up for it.
It all depends what you are looking for in a camera, so far the specs we have seen so far for the G15 have only been rumours, nothing concrete from the horses mouth as it were. We will only know tomorrow for certain what the camera will actually look like and what the specs will really be. Then it will be a matter of putting it to the test before making any comments on the relative merits of one against the other. We assume there will be an official announcement tomorrow because it will be the first day of Photokina but nothing is certain 'until the fat lady sings'!
Unless Canon plans to mess up with its line-up, I doubt the G15 will be better than the G1X.
And the RX100 - all in all - is a more attactive camera than the G1X imho. The Sony is smaller, more classy, features an excellent lens, and there's a lot more tech in it. Canon's biggest advantage - sensor size - is effectively countered by RX100's brighter lens.
Considering that the RX100 is also cheaper... easy win for Sony, as far as I am concerned.