Its not just BFL. Other comapines are developing ASICs and these will hit the network sooner or later. Combined with the reward drop, it will put GPU miners out of business and make FPGA unprofitable in some areas (depending on electricity costs). The BTC price is not dependent on difficulty, so you may not see any real impact in pice!
That's another good point - with a single source (BFL?) shipping - there was huge profit potential to ride the wave before difficulty adjusted enough to get the real numbers.
Suppose you got an sc single 40gh - the first week they ship... difficulty doubles - and you'll pulling 7 or 8 btc a day. average time to find a block solo... less than 5 days.
So your index on difficulty (if they ship 1000 orders a week) factor of : 2, 3, 4, 5 --- in 2 months we're at 10x increase.
During that time you'd earn 8 grand before the network hash rate grew to the point where it normalized.
I suspect that when everything is said and done... a jalapeno will earn about what a decent gpu does now - while a single will make about what I single makes now etc...
But then I'm planning for a 40x increase in difficulty. It's still profitable if you can throw enough of a large enough investment at it. That of course assumes that asics don't kill btc entirely - by forcing gpus out and killing the hobbyists interest in spending btc.