From Claude:
Short answer: a meaningful chunk of the T-bill market, but not enough to solve the deficit problem.
Where things stand now: Stablecoins total roughly $301.5 billion as of late August 2026, and Tether alone reported roughly $141 billion in direct and indirect US Treasury bill exposure as of March 2026, ranking it as the 17th largest holder of Treasuries globally. Under the GENIUS Act, issuers are now required to hold reserves on at least a one-to-one basis with attestation requirements, mostly in cash and short-dated bills — so essentially the whole stablecoin float already functions as T-bill demand. 
The bullish scenario: Standard Chartered projects the stablecoin market could hit $2 trillion by the end of 2028, translating to roughly $0.8-1.0 trillion in fresh T-bill demand over that period. Combined with Fed reinvestment, they see total new T-bill demand around $2.2 trillion through 2028. Even more aggressive forecasts (Citi and others) put stablecoins at $3-4T by 2030 if adoption really takes off — call that $2.5-3.5T of Treasury-bill buying at the extreme high end.  
