Huh... interesting article... So in layman's terms. We're boned if anyone tosses an EMP at us. And the smaller the bomb the easier it is to make a better EMP.
Without significant infrastructure hardening, we'd have to start back at zero for all our power and manufacturing needs.
Well gee... that's not
as bad as being nuked till kingdom come... but still pretty nasty.
The good news is, our countermeasures against such an attack are immune, the only people who could pull it off know that our counter-attack won't be affected, so the only thing to worry about is rogue states. Two of which(Iran/N. Korea) would probably do it if they could, and to hell with the consequences, but fortunately they can't.
I guess... back to worrying about big rocks hitting the planet then. Seems more likely.