The USD has already been in decline as a reserve currency. The only thing that is happening is the decline is accelerating.
It is not necessarily a question of "takes its place", but more about being more serious about diversification. Or to paraphrase the old IBM saying "nobody got fired for buying USD" is no longer the case.
In terms of options you have JPY, EUR and CNY as the big-three and maybe tag AUD on top.
Fair question. And in some circles people would substitute AUD for CHF, and SGD is essentially in the same position as CHF (small, stable, well-connected country).
But AUD mostly because Australia is commodity-rich and so AUD has a naturally high exposure to international trade especially in Asia-Pacific region. Its a bit like CAD but the problem with CAD is its neighbour. ;)
It is not necessarily a question of "takes its place", but more about being more serious about diversification. Or to paraphrase the old IBM saying "nobody got fired for buying USD" is no longer the case.
In terms of options you have JPY, EUR and CNY as the big-three and maybe tag AUD on top.