Gold will continue to be relevant in the economy die to it relatively stable price and since it risk involvement is low gold will be the preferred choice of investment for people will low strength for risk. And just like the silver and the real estate investment it have physical value.
What is physical value ? Why do you think bitcoin is not having such a value ? If you think deeply, gold is just a metal and any currency is just a paper, still why you are considering it will be having physical value ?
Bitcoin is having physical value in electronic mode. If you give USD to a tribal then he may not recognize it. Similarly if you consider bitcoin is not having any physical value, it will show your lack of knowledge. Nothing else.