Harper here to stay.

2) Harper runs the Conservative Party with an iron fist. From what we've heard from those who've left the Tories, there's no room for dissent. Those who would like to rid the party of Harper would be bullied into submission or driven out of the party. The bullying on dissenters would be intense, given that it would happen away from the glare of the media and we've seen how much of a bully Harper can be in the light of day.
3) Even if the party constitution (sic) has a provision for a leadership review after a poor showing at the polls, there's no guarantee that Harper would be replaced during the review. First, the Tories have shown a predilection for ignoring their own rules, so such a review probably wouldn't be allowed to take place. Even if allowed, only delegates who support Harper would be "credentialed" to vote, those who oppose Harper will no doubt be disqualified from voting.
4) There's currently no viable contender for the leadership. None of the front bench oozes intellect or even the charisma that a leader needs. Few of the party's MP's are likely capable of the tact and diplomacy required to hold the various factions of the party together. Add to this the fact that Harper's not the kind of leader who'd let anyone who was a credible threat to his power hang around. He's not likely to groom a replacement, as the replacement would eventually become a threat. Anyone else would be pushed into roles in the party where their obscurity would prevent a serious bid for the leadership if not pushed right out of the party.
So to those who would think Harper's inability to garner a majority government would be his downfall, I'm afraid that they need to think again. Harper's here to stay and won't let go his grip on the party until he's good and ready.