When the price per GH halves, the difficulty goes up to compensate.
Quite oposite. In GPU days, the difficulty adjusted by price, for ASIC it will be true when electricity cost will be major factor
Most miners will mine at a loss because they expect the price of BTC to go up in the future.
Only the uneducated ones that are incapable of simple math.
True, at the moment the purchase cost of the ASIC is probably the most significant risk in mining.
Your assumption is that there will be fewer interested ASIC buyers as the difficulty increases? And that ASIC sellers will have to reduce their price to attract additional buyers?
Simple math dictates that if the price of BTC is such that you take a small loss on electrical costs, say even 50%, the price needs only double and your previous loss is now break even. Simple math dictates that exponential prices are still ahead of us as the market of BTC starts to become a meaningful part of the world economy.
There is already a decrease in interest in ASIC as a result of difficulty increases, and companies are already discounting miners. KnC is charging 2k less for November shipment of a Jupiter than October. Cointerra just announced today that they are offering a 2TH rig delivered in January for $5999. Get a clue.