Perhaps the network is not as decentralized as many think, I believe that one of the main problems for the decentralization of Bitcoin is that more than seventy percent of the mining power is concentrated in Chinese territory, with low number of mining pools with most of the haspower.
Even if the mining rigs were found in the country of China it doesn't mean that bitcoin is not decentralized. Even if they have large deposits they will have no choice but to sell them otherwise their economy will not boost.
So it does not matter if they will store their bitcoins and will not sell them. If that will be the case the price will just climb up and it will be beneficial to us.