Any country that's not actually trying to arrest you or otherwise detain you and where your residence and travel documents have expired will happily put you in touch with a US Consulate and have you shipped home. Edward Snowden (just as a really extreme example) can probably be on plane to the US in 24 hours, should he choose to, revoked passport and all.

Your passport is not your citizenship status. It's the latter that grants you rights and those rights are very difficult to lose. And you can be repatriated with an expired passport (or no passport).

And it seems they are already denying renewals in some cases: https://www.washingtonpost.com/world/the_americas/us-is-deny...