IMO gold will be a common currency again, simultaneously with bitcoin. I know the "winner take all" theory is popular, but, well, it's wrong. What will change is the need for governments to stamp art on the gold because without debasement (taken away by bitcoin), there's no use for that art. People will use little gold pellets and have little handheld machines that vaporize the gold and run mass spectrometry on it to verify purity. The same machines will have built in bitcoin wallets and a QR display.