Having been on the receiving end of first-past-the-post, the Liberal Party of Canada is probably open to some new electoral thinking. Having witnessed the destructive power of a harpercon majority, the NDP will be ready to do anything to avoid a repeat of the vote-splitting that gave a minority of ignorant or stupid voters the power to fuck us all over.
If harper hasn't killed us all through nuclear meltdowns, poisoned deli-meats, tainted water, privatized healthcare, private prisons' brutality, and the reinstatement of the death penalty, and IF Quebec hasn't separated, the Liberals and the NDP must construct a mutually-agreed upon platform designed to last for two years (because Canadians don't like voting). The first thing the Lib-NDP coalition must do is implement some form of proportional representation or instant run-off, or whatever.
NDP MPs campaign in the ridings where they have seats.
Liberal riding associations that want to form a coalition and which have Liberal representation will get to run a Liberal unopposed.
Liberal riding associations with a Liberal MP who do not want the coalition will face an NDP challenger.
Ridings where there's a harpercon will face whichever opposition party scored highest.
Ridings where it's a toss-up can have their local associations meet and decide who to run as a candidate.
harper now sees that Quebec is a source of strength for the opposition. He knows he'll never win it. It's not beyond him to try to drive it out of Canada.