Taking into account ALL of the current preorders, we are looking at 200-250 TH/s. Sure, the hashrate will grow down the line, but if you're talking about a device ordered today (to be delivered after all current preorders are filled), it's not going to grow that much in 4 months. Your payback might be extended 1-2 months is all. It's not like there's going to be a huge rush of orders that magically appear once the preorders are delivered. SOME more orders, sure, but once people take into account the current hashrate, the current payback period, the risk of other people ordering ASICs and increasing the hashrate, and the risk of an ASIC price decrease, I can't see break-even raising beyond 7-8 months for quite some time.
I go back and forth on how much capacity will be added to the network once all the preorders ship. I think a lot of serious miners have their money invested already, but there is probably a significant amount sitting on the sidelines waiting to see what happens. If orders don't continue to come in prices will continue to lower until they do. I would be shocked if the marginal cost of a SC Single was more than 1/4 of what they charge, probably more like 1/6. Six months after launch I wouldn't be surprised to see the Single SC selling close to the price of the current FPGA Single.
