This will never happen. It should be noted that the US president does not have the authority to change the country's currency. Changing a national currency is an extremely complex process and requires approval from multiple agencies as well as congressional approval.

Under the federal constitution, the power to manage the monetary system rests with Congress, the Treasury Department, and is supervised by the Federal Reserve. The only thing the president can do is make a proposal, he does not have the unilateral power to do that.