Worth considering is that 3 of 5 Tories who lost their seats in BC were social conservatives. Also, I don't think it is safe to assume that all Tories will vote against SSM. John Baird and James Moore are two MPs who are on record as being in favour. There are undoubtably more, particularly the Quebec Tories.
The key thing to consider here is that Stephen Harper commands a very narrow minority. With at most two years to govern, he will be looking to translate this into a majority. That majority will come from BC, from Quebec, and most importantly, from the urban areas of Toronto, Montreal and Vancouver. He has to hold this vote, he has committed to it. I'm not convinced he wants to win it. Consequently, I'm not convinced all members of his party want to win it either.
But it will be interesting. And yes, my money is on it happening sooner rather than later, while the Liberals are in disarray.