This may help on a financial / theoretical level, but does not work for real world load leveling of power. The power company can not sell their mined bitcoin to buy power from bitcoin accepting aliens to supplement their supply during peak times. They have to back that up with real world stored energy or additional capacity. I suppose you're thinking they could use this to help justify increasing capacity, but I don't see that happening in reality. That's a large investment with a payout peroid of decades, paired with for a new concept (bitcoin) that may or may not work, especially in it's current forum. What if SHA256 is broken and there is a switch to SHA512 or other? Current ASIC hardware would no longer function, and if a power company spent billions and expected an ROI over 20+ years, this would be devastating.
I wouldn't trust BTC to remain the same over this time scale.