i think the chinese will mint silver coins. mexico might some day too. russia has held paladium but only to keep their production off the market. i would be more inclined to agree with you if i thought other CBs were going to hold silver.
do you read FOFOA? if you subscribe to Another's views, you'd want gold, not silver.
recently, the BIS proposed a rule change to include gold in Tier 1 capital (regulatory requirement). it does not cover any other pm, which is telling. so banks may take gold, but not silver or ag.
don't misunderstand me - 15 to 1 means Ag outperforms Au 3 to 1, and i think Au is going much higher too. I'm only skeptical on it getting past 15.