We need a cryto-currency that people won't tend to hoard.  It needs to hold it's value day to day, but generally decrease in value over the long term in a similar way as fiat currency.  The job of the FED can be accomplished with an open formula for all to see so that it is fair and people know what they are getting.  Money supply can be controlled in real time in response to several factors like "money velocity", "adoption rate", and whatever other economic factors that must be accounted for to keep prices relatively stable, yet slowly inflating.