The dangers we will face (and why some people like the idea of bitcoin) is that we're developing dependence on a financial system entirely controlled by private entities. Your bank that holds your money, to the many companies digital payments flow through, to the bank where your money is going. You are controlled by scores you can't directly influence, and can't challenge. If you're Chex score is too low, banks will refuse to let you hold a bank account with them.

I think accepting cash should be required until we have a system like this in place (I'm US focused, but its the same for other countries): The USPS/Federal Reserve buys/launches a Visa/Mastercard like transaction network and at the same time providing a universal bank that any citizen could use without charge. This would make sure that there is no such thing as "un-banked" people, and would provide a world where we could realistically go "cashless."