Re-read the thread and while the OP which boils down to the question of;
But what if the Soviet Union somehow lost the Battle of Khalkin Gol?
The main "question" is of goals and policy, not so much logistics and numbers. (Important though they be they are in fact a 'secondary' consideration when the REAL question is if either side actually WANTS a war, which for actually pretty similar reasons they did not)
In the main Tokyo didn't want to start a real 'war' with the USSR, probably more so to avoid giving the Kwangtung Army anymore power/support than absolutely necessary as it was a given they'd run with it to their own ends rather than follow Tokyo policy. On the other side the USSR was looking to give the Japanese, (and specifically the Kwangtung Army) a nice "punch-in-the-nose" blow to 'settle' this frontier issue so they can concentrate on the more "important" European front.
OTL the Kwangtung Army nicely set itself up for the blow by ignoring intelligence and underestimating the Soviets willingness to escalate the conflict short of war.
Now suppose for a moment that the Kwangtung Army gets some clues and instead at least takes them more seriously. (NOTE this does not change the political positions, just the "on-the-ground" situation) So that the situation more closely resembles Bob-The-Barbarian/Wiking's scenario.
Suddenly Zhukov is no longer enjoying a tactical 'advantage' on par with OTL and the much more likely outcome that will not be what Stalin has ordained. We assume he has two brain cells to rub together so he would obviously kick the information up the chain to Stalin. (OTL that's what happened when Zhukov initially requested the 'reinforcements' OTL that he used in his offensive)
Stalin now has two choices;
1) Commit more forces to the area which will obviously require they be drawn from resources planned to be committed to "other" upcoming operations. (Poland/Finland)
2) Tell Zhukov to proceed with the forces he has which invariably is a 'win-or-die' situation and "hope" this will still bring the Japanese to the negating table willing to accept and enforce a stalemate on the Kwangtung Army.
Note that "history" has shown that nothing short of a decisive and overwhelming 'defeat' will force the Kwangtung Army to actually abide by such a political agreement so any 'ambiguous' outcome is counter-productive. Japan is unclear at this point that if actually 'war' breaks out if they can either count on German aid or even IF Germany can provide any real assistance. Neither can the USSR prosecute a 'war' at this point due to planned overextension that as we know OTL does not go as planned. Stalin of course can't "know" this but it was quite obvious he'd already committed the most resources he COULD commit to the theater without taking resources from his other planned offenses.
The question isn't who 'wins' now but if the conflict even takes place as we know it OTL as neither side now has the 'advantage' enough to guarantee a 'clear' decision.
(Note the German-Soviet Non-Aggression Pact wasn't signed until AFTER communications from Khalkhin Gol indicated that the Japanese were losing, badly. With a less clear outcome around the same time frame it would seem MORE likely that Stalin would jump on the Pact to assure German non-interference if he has to commit more forces to against Japan at some point. Keeping in mind that Europe will always be the 'main' theatre of attention. However, given a 'less clear' outcome in August of 1939 how tempting would Stalin find it to consider building up forces for a "more favorable outcome" campaign say in late 1940, or early/mid-1941?)
Zhukov has to do "something" obviously and keeping in mind his 'reinforcements' have been 'cherry-picked' from the whole Red Army and it's likely the Soviet forces can still use their tactical mobility, and better logistics to generate a positive outcome but at a higher cost, and probably far less 'clearly' an overwhelming victory as OTL. Or he could be told to simply 'keep the lid on' things while the situation in Europe is resolved. (Then it becomes a question of how long can the Kwangtung Army continue to support the forces concentrated in that area and/or how long before the local commander jumps off on his own again)
Further Khalkhin Gol OTL was a "proof of concept" run for the tactics and organization he used later against Germany.
Randy