Why would the fact that China is basically controlling mining do anything to Bitcoin?
The whole concept of bitcoin was based around decentralization.
If China controlls a large % of the hash power then it would only take the collaboration of a few to hit the dreaded 51% control point
And do what? Destroy bitcoin? It is illogical, they would be the one hurting the most. Chinese miners are not stupid - they too want to earn money in a long run.
Messing with bitcoin network like that would cause huge price drop - therefore miners profit will be lowered.