There are a lot of different scenarios I can see playing out in China, first off none of the major powers want to confront each other but may have to if their interests come in to conflict with each other.
Germany may have to ship troops over to protect the rail lines they want to open up again, the United States might have to send units over to keep the ports open for trade and "humanitarian" reasons, Russia might send troops to support the "newly independent Kingdom of Manchuria", Great Britain might need to send troops to "protect" Hong Kong, and France might have to come to the aid of their former colonies in Indochina.
One of the solutions may be realization that China is too big to govern itself and it may be carved up into different political entities each under the influence of a different major power to ensure that the peace is kept.
On another thread there is a lively debate about the Daqing oil field that was developed IOTL 1957 in Manchuria, has that happened ITTL?