Looking at the timeline of events it seems the road is wide open. If we hand waive the Hitler government and war in Europe, then I would argue that Weimar pursues a similar course of trading arms, munitions and goods for raw materials, the Chinese Army continues to get German arms and training, after 1937 I think the advice gets more openly conducted. Here I assume Germany still sees Japan as an Entente puppet and the Asian enemy holdings its lost colonies so without more overt threat from the USSR Japan has less value to Weimar than Hitler as an ally. In fact China might pull the USSR and Germany closer.
The USA and UK continued to trade with Japan and the British recognized her conquests in China so I think the true aid from them is dicey. So long as the USA sells steel (and scrap iron) with the UK selling oil to Japan the war drags to the stalemate it reached. Without the Fall of France I do not see Japan invading Indochina but perhaps attempting to blockade it? If the UK and USA do not intervene I feel France will curb any shipments of arms but it will break the relations of these nations with France. We might see a Franco-German relationship take root now. But the USSR can offer a land line unless it seeks neutrality with Japan as they did (presumptively only in response to Hitler). If one accepts the Stalin was only interested in reducing the threat of a second front to open the door to war in Europe on his terms then I think the neutrality treaty with Japan exposes him for an opportunist aggressor and Germany will have to move to the defensive setting us on track for war in Europe.
But if the USSR lets the arms flow into China, partly German supplied, and allows trading with the Germans, Japan reluctantly accepts an armistice, spins it as a victory and retreats to hold Manchuria and the puppet states to seethe. China might fracture into a KMT South and a CPC North, everyone would prefer that I think, especially Japan and the USSR. Now the UK and USA would offer aid to "free" China, along with more trade concessions, but the Germans might offer better terms, especially if the French feel this is a better path ahead, the two begin a path to peace between themselves and cooperation in Asia. Mao is a Soviet client until he gets set aside for a more compliant tool and the ROC steers a dangerous course between the Europeans hoping to get strong enough to reunite China and oust the Japanese. Once Japan gets the A-bomb the lines solidify and Asia falls into various spheres of this multi-lateral Cold War.