US is involved in Tariff War with China and aggressive deals with others.
US has substantial long-term trade deficits, so that China and Japan have come to own a lot of US assets.There is an accumulated Current Account Deficit of $3 trillion in the last three decades.
If China loses US markets, if will market strongly in other parts of the world, usually with price advantages.
US Federal Budget is in deep deficit. If the Federal Government is to raise money domestically interest rates will have to rise.
There is long-term pressure on the $ to fall.
World-wide liquid funds can send currencies moving fast.
China has about $1 trillion in US Government Securities. If the $ falls, it loses, and loses trade advantages as well, but it has discretion in that market.
The $ is the main world reserve currency, which gives the US a seigniorage bonus, but it is declining in that role. The Euro and Chinese yuan are also widely used and there could be a more sudden move out of the $.
Trump is declaring trade War on Iran and others, using US market clout. Immediately it may work, but many will learn to do without the US. Iran will sell its oil.
Costs of global warming are increasing world wide.
The rich move their money fast when they will lose out through currency moves. They have holdings in tax havens of perhaps £20 trillion; this may stabilize or destabilize the $.
Disparities of wealth and income across the world make much of the population living precariously and predispose to recessions, because the rich spend less of their income.
The US has spent and will spend several $ trillion on wars and the military. Useless burden.
The 1917 fall in the $ did not help its trade position much immediately.

In the light of these the $ looks weak. A fall creates more problems than it solves for a couple of years – higher costs, difficult Federal Govt funding, etc. There could be trouble ahead.