I tell you, I've been running the numbers, and I'm beginning to wonder if ASIC's are even going to be able to cut the mustard. Figure the most efficient unit announced so far is ASIC at 60 GH/60 Watts for $1,299 and the most powerful per dollar is the BTCGPGA at 72GH/80-120 Watts for $1,069.
So, let's kick in a _conservative_ difficulty increase of 10x, and I say conservative because BFL has already said they have enough orders to bump the network at least that high. With power costs of .10/kwh and a BTC/$ rate of $12.50, the hardware breakeven is:
BFL: 132 Days
BTCFPGA: 88 Days
So at _best_ you're looking at a minimum of 3 months before you can break even, and that's assuming the difficulty doesn't ramp up higher during that time, which is rediculous. I'm beginning to think that if $/BTC doesn't jump drastically or BFL/BFGA don't increase their hashing/watt/$ drastically, you could easily end up in a situation where you never actually break even.
I'm glad others are starting to work this out. Check my post here (which you already responded to):
https://bitcointalk.org/index.php?topic=28402.msg1368704#msg1368704I think diff will go up 50x
It will almost certainly go up 50x, and probably even more. How long it will take to do that is anyones guess though. I mentioned in a previous thread that BFLs own estimates are that they can produce and deliver about 21THash/sec of machines (though admittedly this might go up as they become more efficient) per week. The other vendors considerably less. So assuming that BFL is the sole deliverer of ASICs (averaging the addition of the slower vendors against the slower rate of delivery vs BFL and possibility for not enough orders to max everyone out constantly), that still leaves ~59 weeks from start to finish to reach 50x difficulty increase. At which point machines are still profitable, just less so, a BFL Single SC would net about $60/month. Not that bad really, unless you went into some crazy debt to buy them, which would indeed be bad.
Just to play devil's advocate.