That outcome seems unlikely. Both that AI will remain dominated by USA for a few decades, and that they will use newfound profits to eliminate budget deficit.
And why would they want to default on their debts in this hypothetical future where they've "made it", raking in AI profits from everyone. They would work hard to preserve that world order and not shake things up unnecessarily.
> that AI will remain dominated by USA
The USA has managed to dominate software for decades now. Why would it change? Take a look at the current datacenter investments in the USA vs other countries. It looks very much like the USA will even extend its lead.
> why would they want to default on their debts
So they don't have to share the AI profits with foreigners who hold shares in the AI companies.