Since the 1999 referendum, support for an Australian republic has actually fallen considerably with some polls putting it as low as 35 %, while support for the continuation of the monarchy has risen well above 50 %. Figures are similar in recent New Zealand polls. The current Australian prime minister, Tony Abbott, is a former CEO of "Australians for Constitutional Monarchy" and is a committed monarchist who has even recently advised the Queen to reintroduce the awarding of knighthoods to Australian citizens.
I would say on the other hand that, in my personal impression Canadians in general are actually far less monarchist (or royalist) than many Australians I know. In most cases, the Crown is not really visible in daily Canadian life and most Canadians have an attitude of indifference at best with respect to it. Paradoxically, however, the probability of a republican referendum being held in Canada or a republican constitutional amendment being introduced in the Canadian parliament anytime in the near future is practically zero as, unlike in Australia, no major political party in Canada, with the possible exception of hardcore Quebec separatists, advocates the end of the monarchy. On the contrary, the current prime minister of Canada, Stephen Harper, has actually taken steps to reinforce Canada's link to the Crown, for example restoring the prefix "Royal" to the Canadian Nay and Air Force and holding public ceremonies to celebrate the Queen's diamond jubilee and the bicentenary of the War of 1812 against the republican Unites States.
Overall, my opinion is that, barring any major unforeseen change, the monarchy is likely to outlive Queen Elizabeth II both in Canada and in Australia/New Zealand. In fact, I I see not only Charles, but also William succeeding as kings of those realms.