SeldomFixit;
Australia has much more to gain.
Australia actually punches well above it's weight in the USA.
Australia is the 8th largest investor in the USA (thanks to Messers Lowy, Pratt & others) with US$70BN of investment over there and Australian companies employ over 80,000 Americans.
The USA has investments of about US$130BN in Australia and employs over 300,000 Australians.
I see a free trade agreement as more advantageous to Australia than the USA.