I did my high school years in Hong Kong and I can say that this is a good move on BMWs behalf. Hong Kong people have a LOT of money, it's one of the richest "countries" in the world. Mainland Chinese people that come to Hong Kong have stupid amounts of money to spend, so opening a segment in the mainland is a very smart move. Luxury brands are EVERYTHING here.
Apparently Hong Kong has the highest ferrari per capita ratio in the world.