That will be an expensive flight in full Y!

You could always use/abuse the Aeroplan "one free change per booking" for SE's benefit that goes away next year by booking a whole bunch of flights to YWG on various dates/times that are possibly going to suit you, then cancel all the ones you will not be using. All you need is enough points in your account to cover the flights you book.

(Of course it is that kind of behaviour that is almost certainly causing AC to take away this benefit, but for now it's within the rules).

PS: AC if you are listening, rather than throwing out the baby with the bathwater, it would have been nice for you to modify rather than cancel the benefit completely by allowing a maximum of X changes per year rather than 1 per booking. That would allow the person that needs to change one or two reservations a year to do so while preventing the use I have outlined above.