The $0.46 figure is deceiving though; at the moment the cost of running the blockchain is being paid for by the 4% inflation rate. That cost is being masked by the high volatility and speculative forces controlling the bitcoin price, so you aren't really paying it.

At some point, miners aren't going to be paying for themselves by inflating the monetary supply, and then the cost of what they are doing is going to rise to be more than a centralised database tracking everything. Because the mining process for bitcoin is so expensive relative to updating a database controlled by trusted entities, ie, banks. And that will manifest in transaction fees.