Twenty years ago, on July 1, many experts thought it was possible that Hong Kong could be a positive political influence on mainland China. "What if Hong Kong takes over China?" the Economist magazine asked. "China can and should learn from Hong Kong. It is a pupil, not a teacher," wrote Thomas Heberer, a German Sinologist.

Fast forward to today, it is clear that none of these optimistic assessments came true. The possibilities of a mutual influence have clearly manifested in favor of the mainland.

Under current Chinese President Xi Jinping, China has managed to combine economic liberalization, growth and one-party rule. Hong Kong, on the other hand, could not become an alternative model of society for the mainland, also because it is economically less important for Beijing than 20 years ago.

Beijing does not accept any interference in its sovereignty over the Special Administrative Region. It has strengthened its control over the affairs of the city and is ready to confront pro-democracy and pro-independence forces - a development whose outcome remains uncertain.

What Hong Kong residents and the pro-democracy "Umbrella Movement" activists fear is that Hong Kong will be coerced into acting like any other Chinese city.

"Hong Kong is not Shenzhen," says Victoria Hui, a Hong Kong-born American and chronicler of the city's democracy movement, referring to the Chinese city located to the north of Hong Kong. "There are political as well as economic freedoms in Hong Kong."

Read: Sieren's China: Learning from Hong Kong

Unfulfilled promises

"Many people in Hong Kong are bitterly frustrated by their lack of say in how they are governed," the Economist notes in its June 24 edition.

As Britain started Hong Kong's return negotiations with China in the 1980s, it tried to secure old civil rights and establish new democratic procedures for the people in Hong Kong. Thus, in the joint Sino-British Declaration of 1984, there was a talk of a "high degree of autonomy" and that "Hong Kong would be governed by the Hong Kongers." With these slogans, Beijing wanted to calm Hong Kong's citizens and prevent an exodus in view of an imminent return to the communist rule.

Similar formulations entered the "Basic Law" for Hong Kong that was adopted by the Chinese People's Congress in 1990. According to the charter, anchored in the principle "one country, two systems," the economic and social systems practised under British rule would remain intact for 50 years from the time of Hong Kong's handover to China. It also included provisions for eventual democratic elections for Hong Kong's parliament (Legislative Council) and the head of the administration (Chief Executive), but Beijing continued to delay them.

In August 2014, China allowed a general election in Hong Kong but only among pre-selected candidates. This led to mass protests and strikes that partially paralyzed Hong Kong's everyday life from September to December 2014.

Chinese President Xi Jinping, who is visiting Hong Kong to celebrate the city's 20th anniversary of its return to Chinese rule, admitted Friday, June 30, that the "one country, two systems" formula faces "new challenges."

"In the 20 years since Hong Kong was returned to the motherland, the success of 'one country, two systems' is recognized by the whole world," Xi said in a speech. "Of course, during the implementation, we've met some new situations, new issues and new challenges. On these issues, they need to be regarded correctly and analyzed rationally... Issues are not scary. The key is to think of ways to solve these issues," Xi said.

Read: China's President Xi Jinping arrives in Hong Kong for landmark visit

Increased interference

Beijing is not only controlling Hong Kong's administration, dissident booksellers and publishers have been "abducted" and transferred to the mainland. Their forced confessions in the winter of 2015-16 showed Beijing's increased interference in Hong Kong's autonomy.

Hong Kong's lawyers are also holding demonstrations calling for the independence of the judiciary. In November last year, China exerted its influence on the city's Supreme Court to unseat two elected new members of the Legislative Council who were part of the independence movement. From the point of view of the pro-democracy lawyers, it was a dangerous precedent set by Beijing.

China is also using its influence to pressure Hong Kong journalists, especially Chinese-language media, to report less critically.

The "Liaison Office", according to the Economist, has become so prominent in Hong Kong's politics in the past few years that some see it as a "parallel government." The office is an investor in the media sector, with its representatives attending public events prominently and weighing in on the selection of the newly-appointed chief executive Carrie Lam.

Twenty years since the city's handover to China, the future of the "one country, two systems" model in Hong Kong appears in jeopardy.