What happens when countries pile up debt?

Business Insider interviews Ken Rogoff:  Growth slows way down; and the yuan replaces the dollar.

• When countries hit gross government debt as 90-100% of GDP, problems are bound to arise.
• If countries go too long with stimulus it can leave them in a debt trap and with prolonged slow growth.
• The U.S. has been in 'default' before -- when it went off the gold standard -- and there is no reason why it won't have problems again.
• Banking crises inevitably lead to sovereign debt crises as government