Whether the Chinese authority cracks down on the exchanges really doesn't matter, real Bitcoiners in China can buy and use bitcoins all the same.
Most of them sold their bitcoins back though! Where are they going to get any if the exchanges go down?
This is China with Taobao, anyone can open a shop and start taking payments, thanks to Alipay.
The government has banned the sales of VPN(for GFW circumvention purposes) for years, yet they never manage to effectively kill the business, you basically sold them under a different name and try to win a cat-and-mouse game.
And they can't just shutdown Taobao, no government dares to shutdown a platform that creates 20 million jobs for you.
PS: You don't even have to sell bitcoins itself, you can just sell redeeming code of an exchange, hosted in a foreign nation, which is apparently what BTCChina is doing now.
