I don't think it's possible. Maybe default or hyperinflation will take care of it.
You don't really have to take care of it. Just keep rolling over the debt in perpetuity and make sure that it doesn't balloon into something unmanageable. As long as the interest is serviced, the debt holders might not have an issue. The problem comes when the US won't be able to refinance this debt, but that is highly unlikely.
Way past that point. It's already impossible to pay the interest.