There is merit to the EMP, but not the over-hype. It would take quite a few EMP’s to do the job; one will just hurt us regionally. Beyond that, the NORK’s would cease to exist about 32 minutes later. I’m sure Canada would get in on the action because EMP doesn’t stop at borders. Mexico? I hope they are spared. Maybe their peep’s here will go home then.
You’re right about the consequences for NORK; but, according to the EMP Commission, you’re very wrong about the number of EMPs required.
IMHO, no state will risk an EMP attack on the USA, for the reasons you mention. However, a non-state terrorist might try it. The most likely scenario being a launch from a freighter, within a few hundred miles of the coast. While the U.S.A. would probably glassify NORK, Iran, and possibly other possible conspirators (deployed nuclear subs would still be operational) — that might not suffice to deter non-state terrorists.