Unfortunately with airfare there is no "in general". It depends on so many factors that it's incredibly difficult to predict.
On the one hand, you're looking at a very busy time period which makes seat sales less likely.
On the other hand, with Westjet starting service to Orlando it might motivate AC to reduce their pricing or have a sale.
It all depends on how well the seats are filling up. If AC (or NW) have strong sales, they're not going to lower the price for those seats. After all, if they're likely to sell out then why would they lower the price? If sales aren't going as well as they'd like though, then they might put them on sale for a while.
The only thing sure with airfare is that you never know what's going to happen!