I think we realise the days of Empires and gunboat diplomacy are over. We can't force Australia.
Yes, China still dreams of Empire but, unlike the Russian in Ukraine, they have yet to have their sword blunted by reality.
Aus will make a great Republic. Yes, their whole shtick is the "ordinary bloke doing his bit," whilst you have worms like the Murdochs and Packers roaming the planet. But, ordinary Aussies will show the Yanks how a real Republic should behave. They are outgoing where the USA is insular. They are worldly where the US is introverted.
However, the bigger picture is the Commonwealth which has been a marvel by doing things behind the scenes rather than sabre rattling. However, I do fear for it if the new King does not put his best foot forward and treat its continuance as a top 5 priority.
On problems nearer to home.
Charles has his biggest challenges at home and the court HAS to change. To many outmoded and expensive traits inside the walls. He has crafted the Duchy of Cornwall into a very efficient and profitable ( more than a Billion Pounds annually ) enterprise. He now, in view of modern and not so modern ( going back to the Geogians ) critics has to get the monachy off the Sovereign Grant ( aka the old Civil List ) and make it supportive by the Duchies of Lancaster and Cornwall. Then that would take away that particuar fuel that is always thrown on that particular bonfire. he was always vocal on lesser royals working, not taking.
Back to Australia.
Let the Aussies have everything they need to be proud Aussies, not ex cons. The UK ( and the Jocks have to be in the new Kings sights ) has always had a brotherly relationship and our new post Brexit arrangements prove that.
God save the King and God guide the new Republicans.