Don't be silly governments use gold to back up their fiat currencies and the governments will never accept Bitcoin and especially not to back up their existing currency. Gold will always be of value and used in modern times.
Yes that is right that governments are not in the favor of bitcoin and most of them are favoring gold and fiat for their state but as the time passes they will know that bitcoin is a currency which has more power than any other currency or any other asset so in the future it is sure that bitcoin will replace gold in hat matter.