I've not been a fan of the monarchy for a long time, but recently, I've re-examined that position in light of the relationship between the Crown and the First Nations, particularly those with formal Treaties.
Canada can't abolish the monarchy without negotiating new Treaties with First Nations, Inuit, and Métis Peoples. I see a lot of people who say they want to "just get rid" of the monarchy, but it's not a simple act.
We'd have to completely rewrite our Constitution and laws. As mentioned above, we'd have to negotiate new Treaties. We'd need to restructure our government. It would be very expensive and very destabilizing.