According to a company press release, Mastercard announced a pilot program in partnership with Circle USDC stablecoin and others to allow cardholders to pay cryptocurrency merchants wherever Mastercard is accepted.
USDC will act as an intermediary between fiat currencies and other cryptos in the new system, allowing all merchants to offer card services to cryptocurrency holders while making transactions in fiat currencies only. While it may seem inefficient to convert all transaction currencies to USDC, many tokens are easier to convert to stablecoin than directly to fiat.