President Park Geun-hye and Chinese President Xi Jinping should talk about the aftermath of South Korea's potential absorption of the North at next week's summit, a former senior U.S. negotiator said Thursday, claiming Pyongyang is heading toward collapse.

"At some point, and in some as-yet-undefined way, North Korea will be unable to function, and South Korea will become the successor state," said Christopher Hill, former assistant secretary of state, in a Project Syndicate article.

"There will be a full agenda of current issues to discuss. But given (North Korean leader) Kim Jong-un's abysmal leadership in the North, it might be a good idea to make some time to talk about what an eventual border with a unified Korea would look like," he said of next week's summit between Park and Xi.

Hill, a former chief nuclear negotiator with Pyongyang, said Kim is even a worse leader than his father and his grandfather.

Referring to the latest military standoff with South Korea, Hill said the North's young leader gained little.

"Kim's behavior was much in keeping with that of his father, Kim Jong-il, and grandfather, Kim Il-sung: Create a crisis for no apparent reason and expect a reward for ending it. But, in the latest crisis, Kim gained little," Hill said.

"North Korea received no new food deals, no economic or financial assistance, no help with energy or agriculture, and no warm words from the Chinese. Indeed, it is difficult to see why Kim started this crisis in the first place," he said.

Hill said that Kim "enjoys little personal legitimacy in North Korea" and has executed a series of senior officials. Under Kim's leadership, the North's economy is in shambles and the country's relations with its only remaining major ally, China, have strained, he said.

Kim has also shown no interest in six-party talks on its nuclear program, Hill said.

"North Korea under Kim Jong-un has invested heavily and worked hard to develop ballistic missiles capable of delivering nuclear weapons," leaving the world with "no other choice but to tighten sanctions," Hill said. "Kim Jong-un has walked away from the benefits that would come from recognition as a member of the international community in good standing."

Hill said that many South Koreans are not sure they are prepared to accept the responsibility of absorbing the North, but he believes that the South will accept and ultimately embrace reunification.

"The task will be monumental. The relatively recent example of German reunification offers some guidance, but Korea will have to chart its own course. It will need not only sound planning, but also friends, allies, and partners in the process," he said. (Yonhap)