The US Dollar Index has been on an absolute rip lately and reaching parity with the Euro. This is about to change with more and more people talking about it. Looking at UDN which is a bearish ETF of the US Dollar going back to 2015, we're approaching the lower rail of this downtrend.
There have been many ups and downs, and I believe there's going to be a shift. I don't know what it's going to be, but I can see the US Dollar start to devalue against other currencies, and taking the US Dollar index with it.
UDN is a good ETF to play for this in my opinion. A move below roughly $17.50 would invalidate my idea here.