By the time that happens, Bitcoin will either be relatively irrelevent, or have conquered the globe. If Bitcoin is the global currency, its growth is proportional to the destruction of bitcoins and the net growth in value of all things on the globe combined. Bitcoins will become increasingly scarce compared to assets; if twice as many things are being traded at any one time, there must be twice as much value in the money supply (plus deflation caused by hoarding), and thus coin value must go up if coin volume does not increase.
Just out of curiosity: when/if individual satoshis or so become decently valuable, wouldn't the transaction fees be extreme compared to the actual amount of bitcoins transacted? Or does the fee change as well?
They probably will not be extreme because transaction fees are actually a voluntary agreement between the miners and those who send bitcoins. You can choose not to give a fee, but your transaction will take longer to process because less miners will be willing to accept your transaction in the block they are generating. When no coins are generated as a reward, they will all expect transaction fees, but if they refuse one for being not enough bitcoins, another miner may take it. Thus, there will develop a balance between what we are willing to pay and what they are willing to accept.
So fees are actually flexible as asked by the miners and also optional - is that right?
Basically, yes. But to be more precise, what the gentleman above wrote.
