They shall call the nobles thereof to the kingdom - A more correct rendering of this would be, ‘As to the nobles, they shall call them, but there shall be there no kingdom.’ The idea is, that the kingdom would be desolate; there would be no people to rule. Or, there will be no nobles there who shall survive the destruction, and who can undertake the government of the state. The idea is taken from a government or constitution where the monarch is chosen from the ranks of the nobility. Idumea was formerly governed, as we have seen (see the Introduction to the chapter), by dukes or princes; and it is probable that when it became a monarchy it was a part of the constitution that the sovereign should be chosen from their ranks. The idea here is, that none would be left who could be called to the throne; or if any were left, they would be unwilling to undertake the government of a country where all was disorder and confusion.
And all her princes shall be nothing - Long since Idumea has ceased to be a kingdom, and there are neither nobles nor princes there, nor are there any remains of an organized and independent government.