The previous discussion here:
Perhaps it cannot become a currency, but it certainly can become useful money.
Currency is a subset of money.
My point was about currency as a legal tender, i.e., fiat currencies.
To become a (real) currency, Bitcoin needs to handle everyday transactions, and it seems pretty far away from now. Plus, Bitcoin doesn't have to be mandated (FIAT) so that people will use it.
Since we are under the control of governments then chance of bitcoin and any decentralized currency can become a legal tender in any nation.But people may use bitcoin for buying things if they found it is more beneficial to do compared to fiat money payments.
About the transaction time, I agree with that because bitcoin may not be able to handle huge number of transactions at a same time because the transaction fee will be pushed to inconvenient rates.