100 transactions every 10 mins (conservative estimate) x .5 fee = 50BTC Basically transactions go up and people start adding some BTC to the mix and it will be worth more than the BTC Mining!
A .5 fee? That is outrageous. A plausible future I see is bitcoins worth $150, and 10,000 transactions, 1/4 with a .005 fee. That is 12.5 bitcoins, at $150 = $1,875 per block. Currently you get about $700 a block.
Your right, I was just trying to show in terms to understand that even when a block solved only gives you 12 or 6 BTC the fee's will easily make up the difference imo.