To emphasise your point, this is already happening. It's not theoretical. Data Centres across the world can already get signals from their grid, and will do things like proactively switch to local generators.

Nearly 20 years ago I had such a wonderful debugging experience when the power grid where I lived sent a "switch to backup" message and then milliseconds later a cancellation. The colo's power system got jammed between generator and mains electricity and everything rapidly ran out of UPS backup power and died. I found so many dependency loops between servers that day, took me hours to get things back up and running.