For me, the question of volatility is not addressed sufficiently. It is of crucial importance if Bitcoin wants to be successful as a currency and not only as a speculative asset ("digital gold" is only another word for that).
Apart from a noble few, no one wants to use it as a currency. The majority want to speculate on it.
Speculation tapers off when enough people find real uses for it. You can't force it and it's going to happen naturally anyway. It's going to take time though.
Any sort of widespread currency use will be one of the very last things to fall into place. It has to become a store of value first.