From what I've read... I think macao is a huge potential for bitcoin. Why? Because they have issues with getting money back and forth across the chinese border. I read that they basically have to get paid once they are back in china since they can't bring money across the border or something.
If anything Hongkong should be the next largest exchange.
Bringing money from and to mainland is never a problem in HK. And HK has the best banking network with the Western. If BTC needs to grow in China, HK is the hub for it.