I'm pretty sure that digital currency will replace paper money in near future, but we don't have that suitable coins right now. To replace paper money, a coins must have these followings feature:
1. Scalability
2. Big number of coins and can adjusted for inflation (maybe)
3. Untraceable (you don't want the shopkeeper to know all of your wealth just by checking on the blockchain)
4. Fast blocks (a little bit hard to make without having to find block every seconds).
this is exactly why i think
a cryptocurrency, not necessarily bitcoin, will be the currency of the future. bitcoin as it is cannot hope to support an international economy, perhaps the economies of small countries at best in its current state (with future forks and improvements, maybe even a first world country's). however, bitcoin is an experiment; it has laid the foundation and has shown us the potential of cryptocurrency as well has helped us discover and develop technologies that might very well be at the core of our economies in the future.
one point of yours i disagree with though; traceability / anonymity. i think we should leave transactions to be traceable still; it would simplify tracking funds that may have been stolen as part of a crime and such, drastically increasing the deterrence to crime. anonymity could be implemented to an extent, ie not being able to view the balance of an address without a proper signature.