Still Going Strong

"YES": the 3 leading currencies (Dreamstime graphic)

In 2011 Standard & Poor's downgraded the U.S. credit rating from AAA to AA+. The rating agency cited government debt (then $11.4 trillion) and mismanagement of fiscal policy. Not following suit, Moody's and Fitch, the other two major rating agencies, maintained their triple-A rating on U.S. Debt

7½ years later, outstanding government debt has nearly doubled. Citing this as his reason, Starbucks chairman Howard Shultz is running for President: "I think the greatest threat domestically to the country is this $21 trillion debt hanging over the cloud of America and future generations."

Meanwhile, S&P, Moody's, and Fitch have not changed their respective ratings on U.S. debt since 2011.

But what does the rest of the world think? WSJ -- Dominant Dollar Bests Challengers:

after a drawn-out crisis in the eurozone, and a more recent slowdown in China, the dollar’s international pre-eminence looks safer than ever. Concerns that a U.S. administration with an America First platform would diminish the dollar’s global role haven’t been borne out, either.

U.S. debt may be risky, but the dollar is still on top because currencies, which are an imperfect proxy for national strength, are graded on a curve.

International use of the euro, once the dollar’s clearest challenger, has diminished since the eurozone sovereign-debt crisis raised the specter of default on debts previously believed safe. The euro’s share of global reserves shrank to 20.5% in the third quarter of 2018 from 28% in 2009...

But to make the yuan an international force, economists and investors have long maintained, Beijing must permit freer movement of money across its borders.

Instead, facing a flood of capital outflows in 2015-16, it clamped down on investment outside of China.

You can't replace something with nothing, and the dollar is more something than its rivals.