I believe that all that has to happen in this election for us to finally be rid of Harper is for voters to hand him a significantly reduced minority in which the LPC and the NDP out number the Conservatives. Under these conditions Harper will be unable to endlessly bribe the Bloc with Quebec goodies in order to pass legislation. Thus Harper, not known even by his supporters for being cooperative and conciliatory, will be unable to pass his precious corporate tax cuts and his government will fall shortly after being elected which means the GG will be compelled to give the Liberals a chance to form government. To maintain this government the LPC will not need any kind of formal coalition because all they would have to do is govern with a modicum of cooperative spirit and they would surely be able to keep the government together for several years. Now given Harper's apparently psychopathic hatred for the Liberal Party I don't believe that he would be able to abide the position of Leader of the Opposition in the face of a LPC government led by Michael Ignatieff. Furthermore, I believe that once out of power the real depth of Harper's wrongdoing would be properly exposed with court cases, a number of convictions, and possibly even an Independent Inquiry. Harper and a few of his closest associates like Baird would be finished in national politics and the national nightmare of a PMO that is attempting to destroy our national democratic institutions would finally be over.
Though I am not a Liberal, I believe under these circumstances the Liberal Party would move to strengthen the various independent government oversight positions in such a way that in the future the Conservatives would not so easily be able to manipulate the few checks on power that presently exist in the Canadian government. Though the Liberals have, in their time, suffered from a great degree of arrogance and patronage, they would surely realize that the weak independent oversight in the government was almost the undoing of their party and the country as a whole. Meanwhile the true picture of Conservative corruption coupled with the power vacuum that would exist in the Conservative Party after years of extreme centralization would mean that it would take years for the CPC to rebuild.
This thought experiment would only be meaningful if the voters are smart enough to give the LPC and the NDP a larger number of seats than the Conservatives. If not then all bets are off.