Is it a stretch to imagine that when the Governor General allowed Stephen Harper to prorogue parliament she also said that he better not visit within the next year or she will ask someone else to form a government.
Just as to prorogue is an unusual step to take, asking the leader of another party to form government would be unusual but still possible. I may be wrong about this and when it comes down to it, if asked I wonder if Ignatieff would be able to work something out. However, I would like to see the GG do it. It would be a good way of saying "Shape up! None of you have a majority of seats or votes, get used to it and learn to work something out."