People who think of it as a currency are in a minority. Everyone else treats it as an asset. They hoard it, strive for more of it and would rather spend anything else than that. None of those qualities make for a very successful currency.

For now I'd say it was heavily leaning towards becoming an asset class first and only later could it become a currency. And the inbuilt deflation may make it even less likely to become a currency when it kicks in properly.

As for gold, as long as gold remains the choice for governments and large institutions BTC won't challenge it. It could become the gold of the people though.