The PM is telling half the country to pound sand and expects to survive an election? Over the monarchy? Which doesn't affect 99.9% of Canadians on a daily basis? Any PM who suggested something so ridiculous would get demolished in an election.This problem has a rather easy solution: the Prime Minister stating bluntly that parliament(well House of Commons) would simply refuse to approve anything unrelated to abolishing the monarchy, using his majority(or a coalition) to veto it. If this occurs, BC and Alberta would be seen as the irrational ones, holding up the process for an unrelated issue that has already been ruled out; and they would cave. Same goes if Quebec tries anything.
The PM would (rightfully) be seen as the irrational one. This whole argument isn't going to be about the monarchy, it's going to be about provincial rights. And the PM just took a huge shit on them. There's no way every province agrees to such insanity, and the PM can't make the provinces agree to it.
All any province has to do is say, "Add ______ to the agenda or I say no." Boom, no opening the constitution.