My assumtion is that it will plummet to the ground as supply wil drastically increase.
Bitcoin mining doesn't work like that. The increased hashing will, in the very short term, speed up the generation of bitcoins but only until the next 2,016 block difficulty adjustment occurs. Then difficulty is calibrated right back so that the target of 144 blocks per day is regained. At 50 BTC per block, that is 7,200 BTC per day.
So if BFL were to ship a huge amount of capacity all at once then for a few days or for a week even production could spike to maybe twice normal, but then it goes right back to one block every ten minutes.
The only influence on the price will probably be from those mining operators (and potential mining operators) that had held off waiting to see that there really will be a BFL ASIC produced. If these do start shipping, then those people will be scrambling, using their accumulated bitcoins to place orders with BFL. BFL then converts those bitcoins to dollars, so there could be a flooding of hundreds of thousands of previously saved-up bitcoins reaching market after being used to purchase ASIC hardware.
