Tories can win a minority without Quebec, but winning a majority is quite tough.  Harper was able to do it since the Liberals imploded so in Ontario you had strong vote splits and many Blue Liberals who normally vote Tory swung over.  That is unlikely to repeat itself so due to weakness in Atlantic Canada, and BC being a wildcard, the party will need to win around 20-30 seats in Quebec if they want to win a majority.  In Ontario the Tories can get over half the seats, but winning 2/3 seems highly unlikely.  Off course all things considered the odds are the Liberals will win again in 2019, its more a question of whether it is a majority or minority.