What if major exchanges got shut, perhaps due to legal isssues?  People would have a much harder time exchanging BTC to/from fiat in centralized fashion. The market would get fragmented and really decentralized, with exchange value varying significantly from one location to another due to differences in supply/demand. Perhaps then people would start simply assigning a BTC price to goods/services they offer, rather then to the USD?  This would be a reboot of the current economy, and we would be starting from scratch, but it may be a good thing.  The way things are now, BTC simply serves as an intermediary in fiat transactions.