When I visited Shenzhen, Shanghai and Beijing about 5 years ago, I thought there's no way I would live there.
When I visited Shenzhen and Shanghai about 2 years ago, I thought there were some areas which were pretty nice.
The way those cities were improving relative to how HK has changed these couple of years, I would realistically consider moving there if the right opportunity came along. Of course there are other places around the world I'd prefer, but compared to HK right now, it's quite close.