This can happen.

i) Some USD stablecoin, sUSD, will take over the world due to convenience and freedom from banks to a large extent. You can e.g. pay abroad without asking permission, quickly and cheaply. The US will benefit enormously from becoming the world's currency and will not censor heavily, at least not initially and not in non-US jurisdictions. ii) The stablecoin issuer will buy all treasuries they can afford as backing, where the yield will be risk-free profit. The US government gets a loyal customer for its bonds, unlike Japan where the BOJ has to buy all the bonds. iii) sUSD then becomes a currency with strong monetary expansion but which nevertheless gets stronger (indeed deflationary) year after year, backed by risk-free government bonds. The US will enjoy this for many years and will happily issue treasuries like there is no tomorrow. iv) Other countries' currencies go to zero over time. Europeans will scream, but it doesn't matter. Inflation will very high in most places. v) Bitcoin will only be used where sUSD cannot be used, such as by the entities in the drug economy or by sanctioned governments. That is, Bitcoin is only used in censored/regulated areas of the economy or by the very few people who think long term. vi) In the future this will naturally collapse, but it does not look good for Bitcoin in the short or even medium term.