Well, I consider Bitcoin will become currency in time i used bitcoin to online payment and other online transactions. We can also convert bitcoin to a currency of our country. Therefore, bitcoin can be currency but it is indirect not like the transaction we used in our current currency.
To me bitcoin is from the very beginning created as a currency and from where beginning people are using it for online shopping, now even in some places like Brazil and Japan people even use bitcoin for shopping in their offline shops, because they have declared bitcoin as a legal currency and therefore their offline shops are also accepting bitcoin for shopping there.