If it does, people will panic about their power bill,
Depends on whether you are talking GPUs or FPGAs and ASICs.
With ASICs there's a loooonnnnngggg way before the cost of electricity comes back to being a relevant factor as far as profitability (where you'ld consider unplugging). It was that way with GPUs for a while ( ~ Sept - Jan, 2011), and that will happen again soon thanks to the volume of ASICs now reaching miners. FPGAs eventually will hit that point but even they are still wildly profitable in terms of generating more revenue than the cost of electricity to power them.