One perhaps slightly sensational idea might be that the Chinese government are themselves investing in bitcoin and levering their position to manipulate the value for gains. If you were an entity with the ability to knock 50% off the value of a commodity, then on a whim double the value back up again (ie, you're the Chinese government with the world watching you to decide on speculations), this is what you'd do.

This is why when some above have said "the government aren't that stupid, these remaining exchanges have their days numbered", maybe they have allowed them to continue trading because they don't want to destroy bitcoin, rather play with its price for gains/further understanding of the market and the demographics of its users.

Yeah, very good points there, R2P. And you raised the very essential question WHY they did not stop them, yet(?).

There could be several reasons for that, but I guess it just doesn't make too much sense to speculate at this point. What I certainly believe though is that they will shut those alternatives down by January 31st. I mean their intention is obvious. They do not want CNY being traded for BTC, because the coins then can be used as a tool to export LOTS of Chinese money/capital which is basically illegal, or better said restricted/controlled, in China (as far as I know).  Therefore, it would only be consequent to stop ANY possible method. Otherwise, it would be a proper surprise.

We'll see