There are several issues with Circle’s USDC becoming a national CBDC.
USDC does not have its own blockchain but exists as tokens on several bolckchains.
The number of possible transactions and the transaction completion are pretty low for it to become a wide used payment method.
Fiat collected by USDC is stored in a commercial US bank - pretty small compared to Chase, BofA, Wells Fargo…
The ‘Fed’ is supposedly working with MIT on a ledger technology for CBDC.
If the ‘Fed’ wants to bridge its CBDC to ordinary crypto-currency USDC will be a good candidate.
But if the ‘Fed’ wants to actually strangle the ordinary crypto-market they can deal with a few specific banks - take control of the gates in and out of the crypto-market.