It's entirely possible given how the current Chinese government has forsaken its previous commitment to economic liberalisation and is moving towards more and more state control of the economy. If it moved close enough to the approach of Maoist China (or current North Korea), it could go decades without seeing any meaningful growth in GDP per capita, much as North Korea doesn't see any significant GDP growth.
So somewhat ironically, if the USA/West wins their political battle to liberalise China, China would almost certainly become the dominant nation within the "Western/Modern" coalition.
What are the consequences of default?
It would also mean $33T in assets disappearing from the economy. That's a massive amount that would bankrupt tons of individuals/companies that lent the money. $2.8T of that amount is the social security trust fund which means we need to also instantly cut social security too. $7T of the debt is held by other countries who wouldn't be happy with us either.
Is the US so broken brained on taxation that we can't even imagine it as an option? You know that's still how we collect revenue, right?
By the 2030s the US national debt will reach about $50T. Interest payments could be up to $2T per year if rates stay high. That would be unsustainable. The US would have to either cut government expenses or increase inflation to deal with the debt, both of which would hurt GDP.
Both countries probably have negative outlooks in the short/medium term but I wouldn't bet against China simply due to their much larger population. Their population could start decreasing and aging but they will continue to have vastly more working age adults than the US for a long time to come.