So what happens at the end?

say the bitcoin 21m threshold is reached no more mining and hypothetically someone or a select group of people acquires the entire pot so there is little to no circulation. wouldn't the currency just die? 

unlike gold or oil which is a physically commodity owning the majority stake of bitcoin in the end would actually make you lose the most in the end game as the value of bitcoins is only when its actively being traded.

Good point. If BTC no longer becomes usable we could always trade stuff with silver and Litecoin.

so after btc everyone moves to litecoin then after litecoin its the next lesser currency etc etc. so everyone's just chasing the value of unlimited growth of nothing.

google Zeno's paradox. 

This is why I built a bunker. With a lot of servers.

so basically even though bitcoin has a finite amount due to the trade between different coins every new coin that gets mined is like an unlimited expansion of bitcoin so why would bitcoin hold any value.

looking at it from that perspective how isn't it a pyramid scheme except it is theoretically sustainable due to the fact there can be unlimited growth just by creating a new type of coin to be mined.