That's one worrying part. The one I'm more scared about is: it's not all clear to me what would happen if the network gets suddenly partitioned. With China apparently having a big chunk of the mining power, what would happen if they decide to isolate all those miners via the 'Great Firewall'? And what happens if they keep mining, and after a few months the Firewall gates get re-opened?

My understanding is that the miners are important, without them you can't have a 'liquid market' of transactions, is that right? What's the risk if you loose a huge chunk of miners overnight?