If the price of BTC goes below that most people are just going to quit
and
if those people who own FPGA want to carry the load and make 10-20 cents a day
are mutually exclusive statements
(at $4/BTC most GPU miners will quit, yet there's still $1.5M mined a year)
There you go with your lack of math skills again...
It seems you've totally forgotten about difficulty retargetings, which in the event that miners continue to drop out, GPU's will sill HEAVILY out-perform even the cheapest FPGAs, especially since most of them will be PAID OFF ALREADY or incidental to a gamers rig anyway...
You really embarrass yourself, it's pitiful.