What you don't understand and your missing.
The cost of fpga is expensive so people will hit a certain risk point and stop buying more. Buying 10 FPGA will cost $35k and consume 1000 watts, whereas a gpu would consume much higher wattage 10x more for same hashrate
Also switching over to FPGA most importantly will filter out those millenials or 14 year old gamers that gets "free" electric ,that are just wasting us real miners time and eating into our bottom line profits. Some of us real miners treat this as a real business and we don't need gamers involved looking for to roi for a free gpu to game with.
just a small time hobby miner here, 7 card rig. bought a single vcu1525 for 3.6k USD, i could easily of bought more but want to see how it pans out. dunno what percentage hash we hobby miners represent, any guesses?
as for "gaming only" rigs with one or two cards that mine part time whats that percentage of hash? i would think its pretty low. so i doubt they are eating into our profits.
fpga should help lessen the advantage 90, 45 nm asics that private organizations have in the wild now and are mining privately with. make the cost of asics much more expensive (like needing 14 nm instead of 130 nm to compete with current fpgas, or whatever the numbers are, (sorry not knowledgeable in node sizes of fpga vs old tech asics vs cutting edge asics, so consider these numbers guesses)