From a practical perspective, if there's a simple way for a hardware company to remotely-brick their products (intentionally!), then there's also a way for a huge Denial Of Hardware attack by everyone else and it'll be a Global Lockdown in a completely different sense. If it's a designed in capability (or internally discovered, but kept 'handy'), there's no way it'll not be leaked. And there are far more test-'til-it-breaks hobbyists out there, of no particular allegience, than any company's internal QR department could possibly coordinate for 'good'.
(Also, from a technical perspective, there almost certainly is* a way to accomplish the latter in such an apocalyptic way, it's just probably a rather tricky emergent bug that's not yet discovered (or used) by whoever might have actually worked out one exists.)
Not including the obvious method of planting bogus instructions on how to mis-reflash hardware (there are so many 'driver' sites out there that could be subverted) and getting the gullible end-users to break things themselves, just as careless ones already do.
* - still. There have been scares in this vein, in the past, patched up or otherwise mitigated. And, no, not the one explaine ed in the Good Times warning.