What a great thought - The Republic of Great Britain.
Whenever a government tries to stifle opposition, it means those in opposition have a strong chance of prevailing. As the economic problems mount, more people will question the costs of maintaining the monarchy.
I'm not sure how important the monarchy is to countries like Australia, New Zealand, and Canada. It remains to be seen how those that break away will do economically.
It is possible that we are seeing the last days of the monarchy, especially since the new King is not regarded as highly as the past queen.