Yep, that's probably true.
> 2) This would likely violate most FCC/CE/C-tick/etc. certifications.
IANAL but that doesn't seem like it can possibly be necessarily true, since most computers let you replace the motherboard and wifi card.
> 3) The whole assembly would need to be designed to be field servicable so you could access the circuit boards, which would also add cost (and possible warranty issues).
Not all, but most IoT boxes I've seen already are easy enough to take apart, it's just that there's not much to do with it once it is apart. So I don't think this would be a change.