gold miners would never sell the average amount of gold they get per day for anything less then a day's works costs + a little extra for pleasure costs
EG if they only get 1gram of gold a day then they would price that gold at enough to cover their days worth of food, drink, materials etc. and would never sell less then that price. if they ever did, they might aswell give up..
so true value prices (the LOW price) will always be around the minimal cost of living and working on creating gold/bitcoin.
at the moment the last 6 months have shown $70 is the low point in july and with new asics causing miners to get less coins, means its costing them more to mine, which has caused the LOW of september being $109..
anyone willing to sell less then $109 in september is either not a miner and would sell for anything in a panic.. or more simply, dont care about bitcoins in the first place.
they key when trying to track true value is to always look at the monthly LOW's. anything else is just speculation and profiteering
Your argument assumes that the only people selling bitcoins/gold are the miners. That is not the case, so fewer miners does not mean less gold/bitcoin for sale, and whether miners can make a profit or not has no effect on the price.
my argument assumes there is a tail off of a large amount of people willing to sell, and then there are smaller amount of people that would sell cheaper because to them they dont see bitcoin as having a cost value to them, the way a miner would.. and so theses non miners would still sell at a silly lower then average price, purely due to panic.
but due to the majority having the smarts to know the average miner costs etc, they collectively refuse to sell lower.. thus the price didnt tank to 2c in the last year..