この香港に住んでいる筆者はこう語りましたが。。。 This author said "Some people may argue that saving Cantonese is not worth the effort as it would be better to share a common language with mainland China, which can boost trading of resources and ideas. However, there has been little evidence that sharing a common language provides bonuses during negotiations."
However, in my opinion, people and this female author should not discuss whether it is worth to preserve Cantonese or not but everyone in the world should be able to realize that no Hong Kong people / kids can speak Mandarin as their mother tongue.
If there is no Cantonese language lesson/language school being available in the Hong Kong society tomorrow, how can the Cantonese students from Japan and western countries and Hong Kong people interact and communicate with each other in their daily life and business life, right? Cantonese language school is still being good and very profitable business in Hong Kong.