I met someone in Hong Kong the other night from a publicly listed Chinese Tech company. His company is headquartered in Shenzhen. I wondered whether or not he speaks Cantonese (粵語，廣東話，or more colloquially on the Mainland 廣州話).
Baidu gives a number of eighty dialects, but the specifics of what counts as a dialect and what doesn’t is a doozy. To those hailing from smaller communities, which in China probably means entities containing fewer than 100,000 people, with fewer tongues speaking that particular vintage of local dialect, why doesn’t theirs “count?” To Beijingers for example, the Cantonese dialect that is spoken by about as many people as speak Italian around the world, Cantonese is “earthy.” It is “bird talk.” If a Beijinger wants to amp up the insult factor, they would call a Cantonese speaker, or probably a speaker of any other dialect, a “bird person.”
It turns out he does speak Cantonese- that is his lingo. Anyone who visits Hong Kong and predicts that because Mandarin is more and more commonly heard, means that this comes at the expense of Cantonese, only has part of the picture. Hong Kong's facility in English is what is declining- but with tens of millions+ strong native Canto speakers in the Mainland, and a wider group who speak it as a second tongue (I'm thinking Fujiannese, Guangxinese, Hainannese), Cantonese is doing just fine.