Thinking about the potential problems with Bitcoin, I am doing a thought experiment. Suppose that Bitcoin is successful in replacing gold. The market cap of gold is $9.6 trillion (10^12). At that level, each bitcoin would be worth $400,000. In such a world, let's suppose that people were making $40 transactions to buy things. Then the average transaction would be 0.0001 bitcoins. Assuming a reasonable transaction fee of 1%, this would imply that transaction fees should be 1 micro bit-coin in such a world.
Bitcoin-qt would clearly need to adapt to this. Some miners (payment processors) could offer different terms, and users could choose these payment processors with the
addnode option in bitcoind.
I just wanted to get some feedback on how transaction fees are going to adapt to a higher marketcap.