Well, you could, but you might get some pretty funny looks. Seriously though, there's too many varaibles when it comes to barter and exchange to count out gold/silver coins. As long as there's a chance the economy will recover, coins will retain value. Even more so during periods of hyperinflation. If you have enough essentials stored away you can consider a breakdown period as the perfect precious metals buying opportunity. A can of spam for some gold coins? Hell yeah.