Canada's national identity has never had anything to do with being subject to anything or anyone. That isn't what the monarchy is about now and it wasn't what the monarchy was about in 1867. Remaining a member of the Commonwealth and maintaining the country's monarchy is less like staying in your parents' basement and more like keeping the surname with which you were born. The monarchy is Canada's surname, and just like how having the last name Johnson does not mean that your entire identity revolves around being the son of someone named John, remaining in the Commonwealth of Nations does not mean that Canada's national identity is grounded in servitude (or in 'Britishness').