As far as I can tell, there's no reason to believe fiat currencies/economies are headed for any kind of collapse. The world's economies have weathered the last recession like they did every one before it and are now back on the path of growth and prosperity. Yes, there's always issues to address with the nature of banking, the extent and type of regulations, the security, cost, and speed of transactions, etc, but these are all evolutionary changes that will happen over time, not requiring any collapse or revolution.

With any luck, cryptocurrencies like bitcoin will exist in parallel, allowing a different kind of functionality, and a different sets of advantages and disadvantages, to government fiat money.