Joe Hockey will need to morph into a "point man" for the Asian region to help avert an economically-catastrophic trade war between China and a Donald Trump-led United States.

Mr Hockey's predecessor as ambassador to the US, Kim Beazley, and the former foreign minister, Bob Carr, said Australia's chief diplomatic role had become critical as the Turnbull government reaches out to the incoming Republican president.

Mr Hockey's appointment as ambassador had been viewed in some quarters as a farewell tour from politics, trailing in the footsteps of fellow Canberra veterans like Mr Beazley and former Liberal leader Andrew Peacock.

But Mr Beazley, who handed over the Washington embassy to Mr Hockey in January, said the former treasurer would now need to do much more than provide a traditional diplomatic presence.