I fail to see any limitation in the IMF rules to stop China creating another "denominator" which in its own right is backed by gold. China is also exploring crypto - NEO being a fully China compliant crypto-currency already being utilised by China for government transactions. This in its own right could be another denominator.
I reasonably expect China to walk, with others, from the IMF. They already are making serious in-roads into many third world countries - building infrastructure that is useful to the "poor" country and is strategically important to China, eg. harbours, airports, roads and rail.