up until now i dont know if bitcoin can be categorized as currency,,it just commodity without physical like gold..
if bitcoin a currency there there will be a paper bitcoin,,or anything that has physical..
To be a physical coin it should require lots of money to produce.
Because it requires lots of metals and at least 1 country should implement it.
But as a digital currency it is much easier and you can buy almost anything with the bitcoin debit card.
Implementing bitcoins as a form of physical money have a different requirements that should have a particular country there such things that you must consider like bitcoin must be mainstream so that there will no problem that will come.