The famine is severe indeed if the royal household was affected by it, since one would expect royalty to have greater access to resources than the general population. Perhaps rather than perishing from lack of food, Heth “and all his household” might have died of some kind of famine-related disease or been victims of some type of revolt for allowing such a disaster. A traditional purpose of kings in the ancient world was to appease the gods. Heth had turned away from the true God and therefore had failed in his obligation to mediate between God and his people.
Shez, his successor and descendant, continues the king-line. True to Moroni’s model, if not Ether’s original intent, the return to righteousness also brings a return to prosperity.