What happens: The polls are correct. Undecided voters do not break any differently than the polls show, or, stay home.
Why I think this will happen: PQ voters are more solid than PLQ and CAQ voters. In addition, the CAQ, which has had the momentum recently, has stalled and it's voters are uncertain. The CAQ and PLQ are both having difficulty moving from where they are stuck - around 27.5% in the polls each. One needs to overtake the other, but, neither appears able to do so.
Why I think this wont happen: Voters are uncomfortable with the PQ. The PLQ's second choice is the CAQ, and the CAQ's second choice is the PQ. Those voting for the QS and ON could vote for the PQ but have chosen not to, and the QS and ON are both doing better than expected. Marois' PQ is much more focused on Identity politics than past PQ parties, and this makes a for a much harder "edge" to the campaign and the party, one that should be enough to scare off voters.
PQ - 61 - 32.85% - Minority
CAQ - 31 - 38.54%
PLQ - 31 - 27.85%
QS - 2 - 7.18%
ON - 0 - 2.39%
PVQ - 0 - 0.98%
Aut - 0 - 0.21%
(Aut stands for Autres, or, "Others" in French)