A country, itself, cannot go "bankrupt".
You wanna know how we can settle debts, for pennies on the dollar, today, right now?
Mint a 10 gajillion USD coin. Now, pay all debts. Now, destroy 10 gajillion USD coin.
See? Impossible to go bankrupt, if you're the buyer, generator, and seller of something, and there's always a willing buyer.
I think you're overestimating the performance of the stock market for the next 1-4 years.