How useful is Mandarin in Hongkong and Macau?
The question is in the title ;)
As Macao and Hongkong are primarely Cantonese-speaking areas, how widespread is knowledge of Mandarin? Is it compulsory for students to learn Mandarin?
I'm from Hong Kong and while you can get by with Mandarin (some similarities between the two languages allow better facilities for communication), fluency between these speakers may vary depending on age and social class as it was only introduced as a compulsory subject in schools after the handover.
Knowledge of Mandarin wasn't widespread before that. As everyone spoke their regional dialects and somehow established Cantonese as a lingua franca in the British colony due to most migrants being from Guangdong (Canton) province. I would say between "middle-aged" people, by that meaning the members of Gen X- proficiency of Mandarin generally tends to be lower. Although this might be a huge generalization- some can pick up Mandarin later in their lives.
The Education Bureau has recently (two years ago) provided 8 billion HKD on language learning schemes, and the introduction of Mandarin as a second language due to the rise of China's economy. Additionally, those still in the education system after 1997 will probably have quite an extensive knowledge of Mandarin.
For people born before the sixties, Mandarin was the language of scholars and many fled to Hong Kong during the Cultural Revolution. Thus, those two are probably the largest demographics when it comes to Mandarin speakers, whether native or not.
However this comes with a backlash. The government has been repeatedly been critiqued of preferring Mandarin over Cantonese- for example by introducing simplified characters over their traditional counterparts all the political turmoil, HK independence groups and anti-Mainland tourist sentiment complicates the situation- hopefully Mandarin will still remain widespread.
Judging from most people I've met here, there's about roughly the same percentage of Mandarin and English speakers right now. Though I won't deny- once you've learnt either Cantonese or Mandarin, it's easier to learn the other.
So here's my verdict: it depends who you're speaking with, but almost everyone would AT LEAST have roughly basic proficiency in Mandarin or English- even the Gen-Xers I mentioned earlier. The sociopolitical mess of Hong Kong politics in regards to the Mainland places Mandarin in a precarious state.
I certainly had to learn it whilst a student there, but you won't find yourself too popular if you tried to get by with Mandarin (perhaps a good equivalent might be trying to get around in Quebec with English or Flanders with French). English can be a bit of a status symbol, even, so people with even a rudimentary knowledge of English are likely to be very willing (in my experience) to prefer it, even though I am a native speaker of Cantonese!