In terms of paper currency yes, they will be. More accurately, paper currency will be worthless.
If you have a local network that’s willing to take gold and/or silver, more than likely in terms of real goods, gold and silver will settle down to a certain value, probably not all that different than what it has been historically.
In severe economic disruption, people may not be willing to take precious metal and will stick to barter if they don’t feel they can exchange gold/silver for goods with the next guy.
Even so, it’s better to not let the value of extra cash waste away. Once you can survive, convert the rest to precious metal and wait for better times.
Provided we’re discussing a “barter economy” - No, I mean in absolute terms, practically speaking. Set aside for the moment the likelihood of that scenario.
Anything that needs to be imported would be pretty much unobtanium without an accepted medium of exchange. “Imported” would take on a new meaning, but particularly things not grown or produced in the US.
It seems unlikely that if paper currencies aren’t for some reason accepted
locally then forget things like coffee and chocolate, which can’t be grown here. My view is that such a scenario seems pretty unlikely but if that were to happen, that’s what we’d be looking at, no way around it. Thankfully most of our wealth outside the house is held in T-bills and Savings Bonds. Hm.