Generally unsuitable monarchs have been removed. It is to be doubted that given the current heirs age that he will be able to undertake the necessary duties in all the current realms in another ten or more years. Overseas tours are required and sending the next heir will not be considered sufficient. Any British monarch who loses Canada, Australia or New Zealand will go down in history as someone who could not keep the show on the road successfully.
Well Queen Elizabeth II 'lost' South Africa and this was after a major tour in 1947 to shore up support for the monarchy. George VI didn't really want to go and it was an exhausting tour at that, but South Africa became a republic. QEII also 'lost' Singapore ( a republic), Malta ( a republic) despite Malta being the place where she lived quite happily for a short time and mixed with the locals. That still didn't stop the Maltese from voting in a republic.
George VI 'lost' India, various royals visited frequently.
India and South Africa were far more important ecomonically to the UK than Australia, Canada and New Zealand are. Now those 3 countries are of little economic importance as the UK joined the EU. And in the early 1970's just about devastating the New Zealand diary industry as the UK was their major market and they stopped buying as the Uk was obligated to buy mainly from EU countries. Australians, Canadians and New Zealanders have no advantages in the UK workwise either, unlike EU citizens who don't need visas to work in the UK, Australians, Canadians and New Zealanders do. Having the Queen as Head of State may be symbolic to some but there's no really strong ties, especially since those 3 countries have had large number of non-British immigrants who have no connection with a British Queen.
Why is it that people persist in perpetuating the myth that Australians ( and for that matter Canadians and New Zealanders) are tabloid reading simpletons who will reduce the decision as to what system of government they will live under to a popularity quest? One at that run largely in tabloids?
The Australian referedum in 1999 the "no" vote won but it was not a vote for Queen Elizabeth II. It was a rejection of the republican model on offer, that was that the Head of State was to be appointed by the government of the day. Republicans wanted that the people voted who would be the Head of State. Therefore diehard republicans voted "no" not because they wanted QEII to remain the Australian Head of State but because they didn't want the Republican model on offer. They would live to fight another day ( and more than likely get a Republic where the people vote for their Head of State, one who lives in Australia and not the UK) It's irrelevant who the monarch is in the UK, Australians who want a republic want it based on that the Australian Head of State should live in Australia, not a foreigner who resides on the other side of the world. People's personal lives are also irrelevant Australia already has had a Prime Minister who admitted cheating on his wife and who had been an alcoholic. He was voted in more than once.