I agree with this.
Also, in the case of Australia, this countries demographics are rapidly changing leading to more young non European immigrants, who have zero affinity to the British monarchy.
This from Quora;
Due to the current immigration rate the racial demographic is changing rapidly. Currently about 76% of Australians identify as white or European. That number is decreasing and will not increase again. The percentage will decrease fairly rapidly from here on in. The largest cohort of migrants currently are South East Asians at around 40,000 entry's per year. Chinese are second in number. As Australia has a reduced figure of 160,000 immigrants for this year and Morrison is going to take it back to 270,000 per year for next year it will not take long for the non-European component to rise exponentially.