North Korea's deadly attack on a South Korean island has shattered lingering dreams of peaceful and gradual reunification and the fall of the world's last Cold War frontier, analysts say.

The November 23 bombardment -- the first on a civilian area in the South since the 1950-53 war -- and a flurry of leaked US diplomatic cables have focused attention on prospects for ending the decades-long division.

Some cables released by whistle-blowing website WikiLeaks suggest China would accept a reunified peninsula under Seoul's rule, as long as US troops do not head north over the present inter-Korean border.

Others indicate Beijing's frustration with the Kim dynasty which has ruled the North with an iron fist since 1948.

China has no love for the Kims but wants to keep North Korea as a buffer between it and a democratic, pro-American South, analysts say, although they are divided on just how much influence it wields with its wayward ally.

Analysts also have varying views on whether eventual reunification is feasible. But all agree that it will not be a negotiated and peaceful process.

Events this year and last show that reunification "is more likely to be violent than peaceful", said Peter Beck, an international affairs fellow at Tokyo's Keio University.

He said Pyongyang's current leadership is stable, with a team in place to support leader Kim Jong-Il's youngest son and heir apparent Kim Jong-Un.

Leader Kim, because of his failing health, saw provocations like the artillery attack as "a way for the new leadership to establish its credentials with the leadership and the public", Beck told AFP, saying he fears more of them.

The cables released by WikiLeaks reveal wishful thinking on the part of South Korean and US diplomats, he said.

"The more junior Chinese leaders are frustrated with the North but senior leaders have made a determination to stand with it," Beck said.

"There's no question that China wants to keep North Korea as a buffer state... therefore, the prospects for reunification are distant."

Professor Kim Yeon-Chul of South Korea's Inje University also saw slim prospects of a power struggle after leader Kim dies.

"The North's elites share their fate with the current regime and the path for a power transition to the heir apparent has already been firmly laid."

Jeung Young-Tae, analyst at the South's Korea Institute for National Unification, suggested, however, that the regime has over-reached itself with the latest attack.

He and Beck saw similarities to previous provocations, when Kim Jong-Il was trying to bolster his authority before succeeding his own father Kim Il-Sung.

But the world had changed since the 1980s and 1990s, Jeung said.

The United States is in no rush to return to negotiations, and the South's conservative government has taken an even harder line towards the North given public anger at the shelling.

"Under these circumstances, there is ample possibility that the Kim regime would face considerable difficulty, for instance frustration among the hungry public getting out of control and a power struggle within the North's political elite escalating," Jeung said.

The latest "risky gamble... may come back in the end like a boomerang to hit the regime".

Robert Dujarric, director of the Institute of Contemporary Asian Studies at Temple University's Japan Campus, also saw the North's future as unpredictable.

"At any point it could collapse with little warning. In that case, unification would happen quickly," he said in emailed comments.

While Beijing probably prefers the status quo, it "isn't going to go to war to defend the Kim dynasty nor will it invade to prevent collapse. So to some extent, China's power to influence events is limited."

In August, South Korean President Lee Myung-Bak unveiled a long-term plan for reunification involving a special tax in his country to help foot the bill, which government reports have said could reach trillions of dollars.

But analysts questioned whether South Korea really wants reunification, with its massive costs and social upheaval.

Seoul "wants a non-threatening regime (in the North) at least for a transition period of several decades", Dujarric said.

Beck said the South is unprepared economically, politically and socially for early reunification.

"Almost no one wants reunification soon and no one wants it to be dramatic, messy and costly."