I don't think they are going to establish a new world reserve currency. They are always quite happy with being only the second best. My guess is that they hoard gold just in case dollar should fall. This way their gold reserves will serve a hedge against such a possibility. No matter what currency becomes a new dollar (or even if there is none), they would always have something to exchange for it, or just directly use their gold as money.
They are happy being second best for now. Once they become a developed nation, you never know.
Thinking of the Chinese establishing a new reserve currency at this point of time is far fetched. If you have RMB, you can't even purchase capital assets in China now!!