Gold backed debit cards will likely become very popular, as long as it is allocated backed for delivery metal. That way the biggest criticism against owning gold is eliminated - I could walk into any store and maybe spend a couple grams where the store owner is none the wiser receiving whatever local currency, and a couple grams are debited from my account. As long as it is audited and not ponzified / leased out/corzined/ fractional reserved to the sky.