Yanks are a crumbling empire. As you say, if push comes to shove they will leave us in the lurch. They basically outsourced their foreign policy to us and we failed. Good diplomatic relations need to be re-established with China, regardless of who wins the election.
Where I believe the U.S. went wrong is by abandoning the gold standard and manipulating currencies too much, and also with its aggressive foreign policy including 80 military bases all around the world crowding nations and superpowers in and in combination with using their dollar for sanctions on virtually anyone that looks a competitor and bringing down smaller nations by meddling in their politics putting Muppets in, coups and initiating insurrection and undeclared wars. Their pushing globalization and being the instigators of the so called GFC has ruined many people.
The other thing is the U.S. tends to beggar it's neighbors and allies eventually, look at Japan ,Latin America and now Europe. They will be the big losers for going into bat for U.S. forward foreign policy, when a more balanced relationship with Russia definitely would have kept the peace in their backyard. Now they will really struggle doing America's heavy lifting buying expensive weapons, food, energy from the U.S. to which they are totally subservient.
End result is their losing all their soft power and most worldwide including many in the West don't like them.
And in the end that's where most of their power was derived.
As for a war with China, this is why I believe it was a mistake to go with the subs for 80 billion. Submarines really will be an extension of the U.S. military against China in a forward role far from Australia which is very problematic to me. It is provocative to China .and it means we a an unwitting tool for the U.S.
If war breaks out in Taiwan I can't see the U.S. winning. They would have to keep their carriers well back for fear of Chinese missile strikes. And with our subs lobbing a few missiles in China we them become a target, a rather soft one because China won't attack the U.S..
And we will have to go along with sanctions bankrupting us while we have little industry after the U.S. pushed us along the top of the globalization curve.
And while a detente may gradually occur between the superpowers sanctions will remain and China will forever remember a really shitty small country that turned up in its waters.
That's why I would've invested the 80 billion on another 8 frigates 500 jets and some conventional subs so then we could influence U.S. defense policy in a way more practical for Australia.
Whatever happens, China will always be our neighbors even if the U.S. losses interest in this region.