Bitcoin is not only measured in USD, its value can be translated in other currencies, for example one BTC is currently equaled to 4,064,594.12 Japanese Yen, and of course one could purchase a denomination of BTC using virtually any currency of any country.

As for the last part of your comment, I can agree, your property and skills will be the most valuable commodities should the economy totally tank some day, and oh yes speaking of property... During the years I've been investing in BTC I've made virtually 100% profits, meaning I turned that "worthless" digital money into actual physical cash (aka USD), and then proceeded to use said profits to purchase other physical assets including ammunition for my weapons, among other emergency type supplies. So... remind me again how useless Bitcoin is???

@SpikeTalon good point - I've never seen anyone discuss value of bitcoin in anything other than USD

@SpikeTalon if - not if but when the US economy collapses what do you suppose will be the overall effect on the global economy. Will the Japanese Yen become the preferred currency - perhaps the Chinese Yuan? I doubt the Euro won't have any value and certainly not the British Pound note nor the Australian Dollar.

@iThink I agree with you on the currency becoming worthless part when the economy tanks, and concerning that is. If one has some extra currency to spare then I'd suggest investing in some assets like emergency equipment and weapons and extra consumables. Keep telling people you can't eat gold and contrary to some popular beliefs you cannot defend yourself with silver. When society collapses and everything goes to hell, people will want/need things like consumables medicine & first aid supplies and weapons to protect your assets, they won't have much use for gold and silver. Certain work skills would be more useful than gold and silver.

Too good