The last time the main fed conservative party(s) won more than 50% of the popular vote was 1984, 42 years ago. Since then, not only have the conservatives not broken 50%, they have always held a lower share of the vote than the Liberal + NDP.
The fed conservatives have averaged 36.5% of the popular vote compared to 50.18% for the Liberal and NDP combined in every election since 1988.
If the Liberals actually cared to prevent the conservatives from every holding power again, they would've changed the electoral system. The conservatives would never win a majority again, much of that due to demographic changes, with younger generations being less conservative.
I would be pressing Carney to follow through on Trudeau's promise.