In a true dollar collapse, it means thinks went extremely fucked up. In this case: ammo, weapons, whiskey, toilet paper, lighters, propane, tampons, bandages, dehydrated fruit, knives, cigarettes, motor oil, butane, firewood and candles are money baby!
and then once civilization reforms itself, hopefully Bitcoin is the worldwide currency to avoid a collapse happening again.
i think many will just adopt the second strong currency which is the euro(or the one in third spot, here one of those
http://top10for.com/top-10-strongest-currencies-trade-world/), it's not like they actually care about the dollar, people generally use what is used the most not what it is bette
Indeed, the euro, maybe the Yen. It will be extreme when stuff like alcohol, tabaco, medicines, stuff to make fires and weapons will be the black market currency to get food.
When this happens it will be like those post apocalypse movies. Still, I don't think a fiat collapse will cause this to happen.