With this kind of open information future entrepenurs can use this to spark ideas to start bitcoin bussinesses to accomdate this continuing use of usd/fiat and what bitcoin community needs. Awsome idea.
One reason is that as the difficulty goes up the network automatically decides to reward 25BTC instead of 50BTC thus making it hard to obtain by mining, thus making it more valuable to miners and not wanting to sell them at low values because of electricity costs.
That of course was a really blunt theory but by this time hopefully there will be enough shops to control the value of bitcoins instead of miners controlling the value.
Another factor is bitcoin shops vs cashout to fiat ratio not only is it dependent on the shops but the users aswell. The more shops cashout the less value the bitcoins have since more people will have a lot making it inflate but if its a one time thing the miners will eventually balance this out. Also this is dependent on the miners and the consumers they can control the price if they refuse to buy and boycot a service or product
i think it should be standard procedure for all shops to state whether they cash out or not. would help in studying the market or something