Every week it seems, I read of central banks buying tonnes of...

Every week it seems, I read of central banks buying tonnes of gold. I have not yet read of any country introducing a means of interchange maintained by a block chain in the manner of Bitcoin, if that is what you mean by digital currency.
If you are thinking that gold is losing its allure as a safe haven then just keep observing international affairs with your eyes open over an extended period. If you cannot commit an attention span over a decent period, then just track Trump's pronouncements on trade vs the POG.
Of course, you could buy Bitcoin or its copycats if you want some excitement but best you have a few sets of clean pants with you.`