One of the biggest costs in running mining equipment is going to be power consumption.
So ya, the cost of electricity is becoming much less of a factor than it used to be.
I disagree. Cost of electricity is always the number one concern when mining because you are essentially turning electricity into bitcoins. Cost of equipment is number two, and only matters when you are buying equipment or considering selling it. Since equipment isn't 100% liquid, it's the electricity cost, difficulty, and exchange rate that you are watching on a day to day basis, i.e. "should I mine today or turn it off." Furthermore, if your equipment is more efficient than everyone else's (or your electricity is cheaper) you will be always be able to keep mining, in theory at least.