Ergo, most likely working solution for the 'money of the future' would be something that's reversible. You'd try to get the other advantages of bitcoin in the proper solution, such as instant, verifiable, cheap/free and easily scriptable global transactions - but abandon those that require irreversibility.

The fact that crypto currencies leave a digital trail and verification actually makes it a tad safer than cash if it was a true stable currency which it isn't yet, but one that could offer that between larger crypto currency 'banks' which is what the market does now with real money, the networks and institutions aren't there for crypto currency yet.

Eventually entities will do the exchanging for you in return for the transaction reversibility, just using another currency or crypto credit. Already happening with stored wallets, exchanges and more. Eventually they will be banks. But currently bitcoin is as safe as having actual cold hard cash in your hands.