If USD goes worthless then USDT also will be worthless at the same time because the value of USDT is pegged to USD dollars but in my opinion, USDT will go worthless due to hyperinflation caused by excessive printing before the USD reaches such a position.
USDT as a project generally encroaches on the sacred cow of cryptocurrencies, which consists in the lack of security and the absence of any guarantees. It is this opportunity that allows us to hope for a multiple subsequent growth and contributes to this to some extent. True, this leads to a multiple fall at times, but still there is a future in any case. And USDT is just a business venture that can go broke.