Strangely enough, my family has been running a business in Dongguan (not Guangzhou, but close enough, still a major Cantonese industrial city of Guangdong provi

Strangely enough, my family has been running a business in Dongguan (not Guangzhou, but close enough, still a major Cantonese industrial city of Guangdong province), since 1980s and we have seen nothing like that. You can't say they "refuse" to speak to people in Mandarin because they simply _can't speak_ Mandarin. Back then, many people simply did not have enough schooling to learn Mandarin, and so they simply couldn't speak it (at least not fluently). The government was not stupid. There was utterly no reason to enforce Mandarin and deprecate Cantonese when they were expecting so much investment from Hong Kongers (who usually did not speak Mandarin either) during that period. Cantonese TV stations and radio stations are still doing just fine today. And then of course you can't have just Cantonese when there's an influx of labour from other parts of China, which is why, as a simple matter of economic adaptation, Mandarin gradually picked up. But Cantonese is not being threatened in any way. In fact, there is now a more widespread understanding of the importance of Cantonese, because it is _closer_ to Middle Chinese from the Tang and Song dynasties than many other dialects. It's an important dialect for properly studying and appreciating Tang poems. I know people in more Northern parts of China who know Cantonese songs from the 80s and 90s of Hong Kong because they appreciate the more classical wordings and rhymes of the lyrics.