USD will never become worthless as long as there are still people who want to live in the US and I tell you, there are plenty.
At least not the physical USD notes. I am not sure about the banks though.
USDT is a lot
BTC's value is whatever you believe it is.
story...
Really know that from my views that you USD can't be worthless but certain measures have to be provide in order to convinced readers categorically or stanza by stanza, the only thing I noticed is that can make USD to be worthless is economy of their country, provided that the currency is in existence and coupled with economy, nothing can devalues USD.
See, it's obvious that Bitcoin the values is Paramount, shall from other views everyone can Concord or directly believe in bitcoin via it's regulations of market, because i think the values of btc correlated with cryptocurrency values especially bitcoin.