the production cost doesn't decide bitcoin's price, supply and demand back up it's price
so if less buyer than seller, bitcoin drops lower than the production cost until miners decide to cut loose and stop mining (the end)
Is production cost really an issue? It hasn't been an issue since GPU-mining.
With ASIC mining, it's not that it's inefficient at mining bitcoins. It's that the initial cost is huge, and the difficulty causes the profitability to decline -- unless you buy more ASICs to stay ahead/with the game. But then you're down some more money again...
Vicious cycle; though I do personally know of two people who actively mine. One claims 20,000$ yearly profit, but you won't get near this if you start today without a lump sum to start with.
How much money would you need to buy enough equipment to pay out 20,000$ yearly profit?