To be clear: the consequence is that, the next time around, nobody will lend to us if we need it (which is why we would have to start balancing the budget)?
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.