Currently it cost my BFL single ~$7 in electricity to generate 1 btc. Next difficulty it will probably cost me around $10. My profit will even out at about 11 Billion Difficulty.
I expect it to level off somewhere around there give or take a few billion if BTC/USD stays the same. It also depends on the efficiency of the other miners and their electric cost. There are too many variables right now to accurately predict when it will level out. If BTC/USD were to double then that means I can keep mining til 22 billion difficulty. There should be a point though where ASIC's are barely profitable, just like GPU's right before the ASIC's started appearing.
It cost me about $.55/day to run my single. That's $200 per year. So when it takes me 1 year to produce 1 btc and btc is at $200, I might think about turning it off.
It's really hard to predict anything in the bitcoin world out past 3 months. It's still too early in the game to predict the leveling off point, or how it will happen exactly. We could level off for a few months and no one purchases anymore ASIC's, then BTC could suddenly double in price and well, the network can now support double the ASIC's so people start buying again.
No one really fucking knows dude
The only way we can guess is if we take in enough variables to make a prediction. Who's got time for that?
P.S. If you would like to get rid of a low performing unit to an old timer for slightly above what you think is market value, it would make my lonely single very happy!
