Trump says a lot when the day is long and his statements are usually imprecise and in many cases he tends to say what the respective audience wants to hear, since it is primarily about either attracting voters and/or winning over influential donors.

In any case, Bitcoin will play no essential role as the world's currency reserve at least for the nearer future. That becomes apparent when you look at the numbers.

The current total value of all Bitcoins, also known as market capitalization, is approximately $1.32 trillion.

The total value of all Gold in circulation has a total value of approximately $12.5 trillion - with the current value of the world's gold reserves, which are about 35,939 tons, being about $2.2 trillion.

The combined foreign reserves of all countries worldwide are approximately $12 trillion with the US dollar's share of global foreign exchange reserves accounting for approximately 59.53%.

If the USA were to force the replacement of USD with cryptocurrencies, it would weaken the dollar because demand would decline (USD would be sold in favor of cryptocurrencies), and the financial market would become very unstable as the prices of cryptocurrencies fluctuate very strongly. Regulatory uncertainties and the lack of widespread acceptance also speak against this. Safety concerns also play a role.