Just curious, why would Canada becoming a republic be your worst nightmare. I would love to know your reasoning.
Easy answer: Because I'm a monarchist.
Longer answer: That was a bit of joking hyperbole, there are worse things, I can imagine, like the US absorbing Canada, a zombie plague breaking out, or having a nuclear war destroy civilisation. But being a republic is still up there. If Canada did become a republic, I'd seriously consider moving to the UK, where my father and three siblings live (in Glasgow, though, disturbing to me, at least one of them is an SNP supporter.
As for why I find a republic so repugnant, I'm not really sure. Perhaps it's because my mother's ancestors were loyalists, with at least one captured at the Battle of Yorktown, and their property in Pennsylvania seized, while my father and three siblings currently live in the UK.
TBH, ideally I'd like the UK, Canada, Australia and NZ to join together in an EU-type union, but I'm not going to hold my breath.