> But hypothetically, if a sufficiently-damaging coronal mass ejection occurred, such that we were forced to rebuild Earth's electronics infrastructure and electrical grids from scratch, what design changes would we make the 2nd time around?

I'd guess the goal would be to get things going again as fast as possible so no, I doubt there would be much time & effort put into some of the points you mention, at least in the short term. Decentralization might come not so much by design in an event like that, but out of necessity.