Sounds like the only benefit a home user can get from GPU mining, as noted a few posts up, is availability of hardware, since GPUs are a general commodity more-or-less equally available to anyone. In any other aspect of mining economy we have the same scenario as with ASICs - bulk pricing of machinery and energy will still win out.
Even that argument fails the second that Bitmain manufacturs a cheap interface/motherboard with controller, which combined with their ability to manufacture their own PSUs and buy GPUs in the 10,000s, would give them a significant price advantage on the assets. You can't win this.