This may be bitcoin 101 that I just missed but it would be great if someone could flush out some justification to what Friedcst said about transaction fees becoming a bigger part of the reward for mining a block. Why is it that this will happen? 15 btc per block seems like a lot in fees. What sort of fee per transaction would that equate to?
I'm wondering about this too. With BTC being widely adopted, its value would have to increase to support a dramatic boost in demand and usage. If that's the case, transaction fees will be lowered as its value goes up.