Having regional currencies on a planet as small as Earth seems pretty archaic/tribal IMO. The currencies in Star Trek--which is only set a couple centuries or so from now--tend toward covering entire planets/species/interplanetary alliances/etc.
In my spare time I've been working out some ideas on space colonization, from a planning methodology I think could be key to enabling a serious effort, to yet-another-crazy-idea for a low-cost launch technology, to a legal framework for space communities (orbital rights of way, responsibility for debris, etc.), government, finance, etc.
One thing I've realized is that while a single cryptocurrency would work between space colonies in a given planetary system, they would not work between communities across the solar system due to the time lag. So while earth-moon system colonies might share bitcoin with earth inhabitants, colonies around Jupiter would need to rely on an altcoin for day-to-day transactions. (They could still tie into bitcoin, but it would be like mailing a check as opposed to near-instant transfers.) Oh, and crypto would be ideal for space colonies. (If they can't maintain their electronics capabilities - see below.)
(Off-topic aside: One thing I've realized that doesn't seem to be generally appreciated is that if launch costs remain high, it inexorably follows that the first generation of space immigrants will be heavily focused on bootstrapping up their manufacturing capablities in space. They will lack specialized manufacturing capabilities apart from essentials, and those will be simply made. Thus, for example, they will be wearing cotton or synthetic "homespun" clothing, have a serious lack of personal computers/electronics that we take for granted (excepting mission-critical technology), household goods will be crudely and simply made from a limited range of raw materials, etc. And don't even get me started about the toilet paper. They will work their butts off trying to improve their difficult situation.
It will be more "Amish in space" than the shiny-clothing hypertech societies that films and SF books depict, until a sizable population with diversified raw material inputs and manufacturing capabilities develops. Or someone figures out how to lift cargo into orbit cheaply.)