I agree that the CPC under Scheer is likely to fail to win government in 2019 but otherwise I disagree with your conclusion.  I think, if in fact she has her eye on the really big prize (PM), she should earn her stripes by being seen in the trenches with the troops during the defeat of 2019 and then present herself as the redeeming new CPC leader in time for 2023.

Otherwise, she runs the risk of being labeled as the opportunistic, carpetbagger outsider in the contest to replace Scheer.