Apparently correct, except that Auntie appears to have survived. A cautionary tale for our own would-be ruling class. It ain't easy at the top for fun-loving totalitarians.
From the NY Times article you linked to:
“Typically, the entire extended family of a traitor is executed or sent to a prison camp in North Korea, but analysts have said that Kim Jong-un would be likely to spare Ms. Kim. She is the only sister of Mr. Kim’s father, Kim Jong-il, who ruled North Korea before him.”