according to section 41 of the Constitution Act, unanimous agreement among the Senate, House of Commons and the legislative assembly of each province is required to remove the British Crown as the head of state.
I was reading a while ago that Canada has the crown more entrenched in our constitution than in the UK itself. They just need to pass it through parliament but our confederacy is in serious jeopardy trying to come to a unanimous agreement otherwise.
If they decide to abolish that puts us in a precarious situation.