Who's going to offer bitcoin? Nobody living in Argentina has any to offer. American and European tourists? Why wouldn't they keep their (appreciating) bitcoins at home and just offer to pay in Dollars or Euros?
They can bootstrap a Bitcoin-variant on a new block chain, and have plenty and plenty which are calibrated to the local economy rather than the Western economy.
Remember, money doesn't have intrinsic value. There's no reason a bunch of pissed off middle class educated people can't en masse adopt a new way of trading resources.