Yes I think Air Canada will end up ok.
Note that the announcement is for a Letter of Intent (LOI). There are no firm orders yet at this stage. We don't know what conditions are attached to the LOI.
I'm sure Air Canada will insist on many concessions / guarantees from Bombardier and/or the government before converting the LOI to actual orders.
Another aspect is that reports say AC will use the CS300 on routes currently served by E190s. So that's rather puzzling in terms of size, range and cost.
Even if they end up converting many of the orders to the smaller CS100s they must be getting a really good deal from Bombardier to operate the CSeries on pure regional jet routes.
Another sobering thought is that Bombardier needs roughly 70 more deals of this size just to make its financial targets for the CSeries...