The 7200 BTC minted daily (compared to the 3600 after the block reward halves) should also be seen in light of the current trading volume of the bitcoin economy. If half of the miners currently sell the BTC they earn from mining, it's 3600 BTC per day. Even if all miners sell their mined coins, it's still only 7200 BTC sold per day. Selling 7200 BTC currently, the price would drop from 5.25 to 5.04. That's a 4% decrease in price. But that's a daily 4% decrease. If only 3600 BTC were to be sold each day (after the reward halves) the downward price pressure resulting from miners exchanging their newly minted coins for dollars would only - at the current market situation - cause the exchange rate to drop to 5.08 BTC. A 3% decrease in price, per day.

So the result of a halving of the block reward will be a smaller downward pressure on the price from miners only selling half the amount of BTC that they were selling before. But the effects of this are impossible to determine without knowing how many BTC are bought per day (and kept), as this would have the opposite effect on the price. The magnitude of these two opposing forces seems to determine the effect a 25 BTC block reward will have on BTC prices.