Last Saturday, upwards of one million demonstrators flooded the streets of downtown Seoul, demanding President Park Geun-hye’s resignation and making one thing demonstrably clear – public will is now the single thread by which the presidency hangs, and it doesn’t look good for Park.

Beijing, however, is no doubt enjoying the show, given that the three men next in line are all vastly more attractive options for China, especially when it comes to the issues of whether to deploy the antiballistic missile system known as THAAD or sign the intelligence-sharing pact with Japan known as GSOMIA.

The scandal surrounding Park relates to whether she allowed her longtime friend, Choi Soon-sil, to influence state affairs, forced conglomerates to furnish her retirement slush fund and whether she is in thrall to a cult led by Choi. There’s no strong evidence of any of this yet, but the blood is in the water and the sharks of political opportunity are circling.

More on Park Geun-hye

“We may see her resignation, followed by immediate re-elections for the next president,” said Kwon Hyeong-ki, professor of political theory at Seoul National University. “This is the first scenario. Many are calling for this process right now.”

But, Kwon says, there’s another possibility. “Park may retreat and surrender any real power to execute laws or policies, allowing a newly selected prime minister, chosen by the opposition leaders, to coordinate state affairs until the end of her term [in December 2017].”

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Kwon added: “But this second scenario is more and more unlikely because mass protests are growing, so time is running out. Either way, it’s almost impossible for her to maintain her original power.”

Watch: pressure on South Korea’s Park mounts

This is good news for China. Park has, after all, proven to be a thorn in Beijing’s paw by relentlessly hounding North Korea, China’s ally and buffer against the West. She shut down the Kaesong Industrial Complex, a collaborative economic venture between the two Koreas, toured the world collecting support for the harshest-ever UN sanctions against the North, passed a law to document Pyongyang’s human rights abuses and said in a speech to North Koreans last October: “Come to the free land of the Republic of Korea at any time.”

She has also enraged Beijing over the THAAD and GSOMIA issues. THAAD, the Terminal High Altitude Area Defence system, is developed by the US military and Park plans to deploy it in South Korea to defend against the North, but Beijing believes its radar could be used by the United States to spy on China. Beijing is also wary of Seoul and Tokyo’s GSOMIA, or General Security of Military Information Agreement. On these issues, any of the top contenders set to replace Park would be an improvement in Beijing’s eyes.

Foremost would be UN Secretary General Ban Ki-moon. In a poll conducted by the JoongAng Ilbo in May, 28.4 per cent of respondents said they’d like to see him become Korea’s next president, which is more support than any other person in the poll received. Beijing would probably favour a Ban presidency. He hasn’t commented on THAAD or GSOMIA, but he has historically favoured handling North Korea with kid gloves and said during his campaign for secretary general that he wanted to meet Kim Jong-il, North Korea’s late supreme leader, in person. Also, in 2007, he refused to let Taiwan into the United Nations by that name because, he said, Taiwan is a part of China.

Then there’s Moon Jae-in of the Minjoo Party, who was ranked second in the JoongAng survey with 16.2 per cent, and Ahn Cheol-soo of the People’s Party, who ranked third. The deputy leaders of both their parties submitted a motion this week calling for Defence Minister Han Min-koo’s dismissal after Han provisionally signed the GSOMIA. As for THAAD, Moon recently said the most important thing regarding the matter was not souring ties with China. Plus, there’s the fact that six Minjoo lawmakers recently flew to China on their own to commiserate with Chinese leaders over THAAD. Ahn Cheol-soo, meanwhile, said in July that with regard to THAAD, there was “little to be gained and much to be lost”.

Watch: Massive protest heaps pressure on South Korea President Park

“The Chinese government hopes any future Korean leadership or decision-making process could stall or change plans regarding THAAD and GSOMIA,” said Kim Tae-hyo, professor of international security at Sungkyunkwan University. “But as long as Park Geun-hye stays as the official administration, that stance is not likely to change.”

He said China was aware of the opposition parties’ alternative viewpoints and that, for now, China “cautiously watches and wishes these alternative opinions will win over”.

David Volodzko is the national editor at the Korea JoongAng Daily