Gold has failed as a currency, it wasnt removed by politicians and bankers. The Kings in in medieval times already started to reduce the Gold % of a coin since Gold was way to rare to satisfy the market with enough pure gold coins. Many wars in in medieval times started for the reason of acquiring more Gold for the Market.
You are right. There where times in history whene gold was realy rare. But bitcoins are not gold. If bitcoins become rare, and they will as more people starting to get/use them, then the value of bitcoins will increase and you got your deflation. I agree untill this point. Unlike gold bitcoins can be devided again and again and again. So if bitcoins become rare maybe in future people will be payed in µBTC or even nano BTC. And if this is still an to huge amount you can start deviding also an single Satoshi. This is limitless in theory. It is still not implemented yet but i am sure it will if there is an need to get smaller amounts of bitcoins. In contrast to gold or any physical currency this are just numbers. It does not matter how small they are to represent an value. So i see no danger in hoarding bitcoins.