Let,s say that Harper decides to hang on to power. He tries to cobble together enough support to do so, but this is not likely, as the leaders of the other parties have clearly indicated that they are not interested and that their formost desire is for him to leave. Harper ( like Diefenbaker in 1963), convenes parliament, have the GG read the Speech from the Throne to open the new session but ( like in 1963), the other parties introduces a motion of non- confidence and join together and vote in favor of the motion and it is passed. Harper's attempt fails and now it is in the hands of the GG.
The Governor- General can decide that a new election must be held but that is not likely. Instead, he will ask the leader of the party with the highest number of seats, whether Liberal or NDP to form a government. That leader may , if he chooses make a deal with another party or parties to try and get a majority ( like Pierre Trudeau did in 1972, when he got the support of the NDP , in return for Supporting some of their policies). Or he can form a coalition government with the support of one or more parties ( there has not been a formal coalition government in Canada, since the First World War). The leader of the NDP has staed that he is willing to talk to the Liberals to form a coalition ( it happened in UK recently between the Conservatives and Liberal Democrats)', but The Liberals have non- committal so far ( perhaps they are hoping to win a majority, but that is unlikely)
So, on October 20, there will a scramble to form either a government. Harper can try to hang on, like Diefenbaker and await a vote of non- confidence or he will accept defeat and step down. Trudeau will then have to decide whether to go it alone( if called upon by the GG), or they can strike a deal like in 1972.
Canada will benefit , whether it is a minority Liberal Or NDP or better yet, if they decide to form a formal Coalition. I choose the latter.