A decent GPU would still be plenty profitable even after a 3x difficulty increase. For example the HD 7970 (about $400) currently mines $130/month, with electri

A decent GPU would still be plenty profitable even after a 3x difficulty increase. For example the HD 7970 (about $400) currently mines $130/month, with electrical costs around $15/month assuming a worldwide average rate of $0.10/kWh, making a $115/month profit. After a 3x diff increase, this would turn to $45/mo revenues and $30/mo profits. However this 140 Thash/s of Avalon chips is just a fraction of what is about to hit the network. All ASIC vendors combined, plus future Avalon deliveries will push the difficulty far more than 3x higher in the next 4-6 months. Current ASICs do 150-200 Mhash/Joule (at 12V). Much better than GPUs topping out at 3-4 Mhash/Joule (at 12V).