A country that controls its currency can always bail itself out of all debt by printing all that money. Now they would destroy their whole economy in the process because of inflation and countries being mad about a country doing that. If they don't pay and default they kind of also piss everyone off and that makes the curency rates fall as well. In that case they would repay as much as they want really, the price for not doing that is economy strengt. The dollar could lose the global currency status either way, fun!

Inflation doesn't really capture what would happen.

Debasement is the appropriate term.