The future of silver and gold is bleak. Technology continues to improve mining yields on earth and over the next few decades we are likely to see a flood of precious metals from mining in space. Robots will be doing it and while it will be slow at first, as robotic ships build more robotic ships it will grow exponentially. Over the next century the value of gold will plummet. https://www.sciencefocus.com/space/space-mining-the-new-goldrush/
The future stores of value will be something like digital currency. It might not be bitcoin in a century, but at least bitcoin is leading the way.