RIP. As a Canadian I've always liked that we technically had the Queen as our head of state. I wonder how attitudes will change now that her 70 year reign.
The Monarch of Canada is a ceremonial position. The Monarch's representative (the Governor General) is appointed by the Prime Minister and has no real power (see: the King-Bing Affair for legal precedent), and therefore could technically be done by anyone from anywhere (even beyond the grave). Politically speaking, absolutely nothing would have to change. The Monarch's effective power in our political system would go from basically zero to literally zero, thus eliminating an avenue for potential abuse of power that we risk by keeping a living Monarch as head-of-state. We could achieve this without having to re-open difficult constitutional questions. Traditionalist Canadian institutions with "Royal" in their names (Mounted Police, Army, Airforce, etc) would not have to change their names or branding. Heck, we wouldn't even have to change the designs on our money. Literally nothing would change except closing a loop-hole (albeit a very low-risk one) for potential power abuse in our political system.
The only down side is that smug know-it-alls can say "actually Canada is not a democracy, it's a Constitutional Necrocracy"