In case you were wondering, he's probably banking on the Liberals falling apart as much as anything else.
As the week goes on, the "our faction at all cost" forces within the party are going to get rowdier and rowdier at the thought of either Dion or The Other Guy taking the lead. And, in turn, as things get rowdier, they're going to start pushing harder and harder for Their Guy to take the helm. Which is going to make the Other Side push Their Guy, and so on, and so forth.
The solution was, and is simple: Let Dion do it, with the understanding that he won't act without the consent of his caucus. He is neither Iggy's man, nor Rae's man, and isn't even likely to stay in politics after this is all over. He is, thus, the perfect caretaker here. Especially if the Coalition is waiting out Harper's replacement.
Though, if you think about it, that makes things a bit different. Part of the reason the leadership race was this Rae/Iggy affair was that they were both anxious to deal with Harper. If Harper's out the window, though, and the Conservatives are embroiled in their own leadership battle, the Liberals will likely see much more fertile ground. And, in turn, the Conservatives will no longer look like the staid, stable party that they professed to be under Steve-o. They'd be as chaotic as the Liberals, maybe even more so.
Canada could end up as changed by the middle of next year as America will.