In GDP race, the Greater Bay Area could overtake UK and France by 2035

Reciprocity, not uniformity

"Two systems" allow room for regulatory autonomy and reciprocity rather than complete uniformity of treatment, despite being under "one country". For instance, making border control less cumbersome while preserving the "one country, two systems" principle remains a tough balancing act for China, in our view.

Another point of contention is the social impact of greater integration. The availability and ease of obtaining visas for the Chinese mainland people to visit Hong Kong, for example, has been a source of tensions among Hong Kong residents who have faced the social strain of an influx of mainland visitors in the past decade.

The perception of not acting in line with the "one country, two systems" could erode Hong Kong's competitive advantage and unique contribution to the GBA over time, and also have tangible implications, such as closer scrutiny by the United States under the US-Hong Kong Policy Act, which allows the US to continue treating Hong Kong as a separate entity from the Chinese mainland when it comes to international commerce.

We believe Hong Kong has plenty to offer to the GBA. The benefits from city-cluster development will likely be transformative for Hong Kong in the coming decades, especially given the existence of an official strategy for Hong Kong to participate in the mainland's long-term development.

Kelvin Lau is a senior economist for China at Standard Chartered Bank (HK) Limited, and Ding Shuang is the bank's chief economist for China and North Asia.