If USDT disappears it will have no impact on the market. FYI USDT is a stablecoin. Just convert it to another stablecoin. End of story.

Tether (USDT) is the largest stablecoin on the market, with a market cap of over $120 billion. Its promise of 1:1 peg to the US dollar makes it a key player in the liquidity and transactions of the crypto ecosystem. However, its dominance raises crucial questions: is USDT a ticking time bomb or the anchor of stability that the market needs?
Transparency and Audits: Tether’s Achilles Heel?
Tether has historically faced criticism for its lack of transparency regarding its reserves. However, in 2024, the company released audits conducted by independent accounting firm BDO, revealing record first-half profits of $5.2 billion and significant reserves in U.S. Treasuries. Additionally, Tether completed a System Organization Control (SOC) 2 Type 1 audit, marking a breakthrough in its security compliance. (Binance)