Speaking as a Canadian who's also living under the crown, it's complicated, exceedingly expensive and not really worth the work. In the context of Canada, it would require renegotiating an exceptional amount of treaties and the like, opening the door for provinces to start requesting changes to benefit themselves. Things get even more complicated with Québec involved.

I can only imagine the UK having magnitudes more history than us, it would be even more expensive and even more complicated.

With that said, maybe we can just write a law that ditches the current royalty and replaces them with something like an inanimate carbon rod?