I think bitcoin is used for online transactions and bitcoin prices are unstable, but if bitcoin becomes stable it may be possible that bitcoin will be the currency, but currently bitcoin can not be currency due to the inaccessibility or absence of assets to guarantee it from undesirable risk.
i think bitcoin price wouldn't be stable, because there's still a manipulation prices over there, the fluctuation of bitcoin itself that make something like this happened, and i also think that supply of bitcoin also affect into this stuff. just look on the other world currency like USD, JPY, GBP, did they really have supply ? i don't think so.
So if bitcoin have an unlimited supply, and the goal of bitcoin is to become a new currency i think that's still possible