It will be fascinating seeing the Japanese navy circumvent the Phillipines to fight in SE Asia.
As for Mongolia,its economy was primarily agrarian,what little oil was produced was insignificant and practically nothing for Japanese needs.
That still doesnt resolve the issues of:
1.Japan having no oil to maintain its offensive capabilities since its attacking worthless wasteland in the Far East.
2.Soviet divisions being formation for formation superior to Japanese ones in doctrine,tactics and technology.
3.Soviets having plenty of strategic depth to withdraw into if neccessary with the Japanese not really being able to do much about it since they would need to literally march thousands of miles to get anywhere.Past Vladivostok there is nothing of value that far east.So that front is entirely irrelevant to the USSR's survival because Japan cant do anything there that would existentially threaten the USSR.
The most developed industry in Mongolia at the time was farming,so if you think a load of food can save Imperial Japan be my guest.
The oil itself is neither developed enough nor infrastructuraly supported enough to be of any value to Japan even if it was captured 100% intact,which it wouldnt be.
And yet the Soviets accomplished that fine before Stalingrad alone since the USA wasnt really in any position to send them anything useful what with the Pacific front collapsing.
Again the Soviets were shitting out masses of tanks,guns and artillery before Stalingrad started,the serious US lend lease was useful for stuff like Bagration which required rapid manuvers but it was next to redundant for the defensive operations the Red Army had to do before that combined with the crawling methodical advances they were doing historically.
The deconstruction of the German industry was actually more of a total farce since most of them were never re-assembled.
You will notice that despite stealing all the high precision machinery Soviet designs didnt become anymore sophisticated or fancy.
What material losses?
Nagants,shells,,T-34s and T-26s?
The Red Army had to expend that stuff anyways just to hold onto Stalingrad,by the time the Wehrmacht was bogged down they had the choice of either attacking the flanks or letting themselves be overrun,this wasnt a matter of choice but of military neccessity.
The Germans were a spent force,they couldnt attack even if they wanted to,their Caucasian drive literally ran out of fuel.
Air superiority was something the USSR could handedly live without given the Germans couldnt see their operation preparations even when they had total air supremacy.
You seem to be confusing the Wehrmacht for some mythical uber mechanized army capable of actually doing anything in late 1942 besides dying.
They had nothing left,their reserves were spent,their oil ran dry in the Caucasian drive,they had no strategic depth to speak of.
The Soviets had spies infiltrating every echelon of the German military,they knew the situation perfectly,hence why they acted.
The Red Army proved in Rzhev it was perfectly fine with expending masses of men and equipment into counter-offensives regardless of cost,they quite simply didnt give a flying f*ck.
You are once again ignoring just how massive the disparity of men and equipment between the USSR and the Third Reich was in 1945.
This is a perfect measure of how much additional stuff the Red Army can afford to lose and still win.
The Red Army in 1945 had 6.5 million men deployed on the Eastern Front
The Wehrmacht had barely 1.9 million,a significant portion of which was f*cking Volkssturm and Hitlerjurgend.
The Red Army still has plenty of space to go before its depleted,the Wehrmacht is f*cked.
For emphasis the German forces deployed to the West were 2 million at their peak.
Then we have to count various suppressed peoples like the Yugoslavs,Poles,French etc tying down further Axis divisions.
Then we have to consider that a significant portion of the Axis forces in the Balkans were busy fighting the 800,000 strong Yugoslav partisans and proving utterly incapable of crushing them.
Then there is the issue of the German's friends being unreliable and near worthless.
Then there is the issue of the surviving British Empire being able to actually threaten the European Axis if it starts withdrawing too many men to face the Soviets,given the only people in the European Axis who can effectively fight the British are the Germans.
That same falacy drove the Reich into destruction.
You also assume the Reich and Japan can survive till the 1950s.They cant.
The Japanese are bonned on the Chinese front,which would only get worse when the combined effects of Soviet assistance and total lack of resources took their toll.
On the German front meanwhile you have the fun issue of Adolf probably dying not long after 1945 which will cause a total civil war among Axis ranks combined with half the European Axis actually being occupied territory which the Germans have to constantly suppress and exploit.
The USSR however is 1 united totalitarian state with infinite resources,massive manpower potential and 100% unified political leadership.
You do know the Mannerheim line was smashed right?
And yet they werent capable of doing that years prior.
The Japanese were consistently pathetic when ptited against Soviet and American formations,what luck they had against the British was mostly due to total operational surprise since the British didnt believe the Japanese would even mount serious operations in places like Singapore.
And you still keep ignoring the 1 giant elephant in the room,CHINA.
The Soviets are going to send everything they can spare to their Chinese friends,including actual military advisors.
If China gets even slightly more competent the Japanese are going to be overrun,as started happening anyways in the 1940s.
Those oil fields are nowhere near as large or developed as you think they are.
The wikipedia page for Mongolia at the time doesnt even mention oil,their primary economy was agriculture,there is nothing of value there.
And the Japanese most certainly cant do as they please,they can either follow the rail lines or walk 1000 km,and the soviets will be wrecking the rail lines as they withdraw.
So you get a stalemate either way due to simple distance and lack of infrastructure combined with the Red Army not being total idiots and the Japanese Army being actual idiots.
Japan isnt going to take the majority of Siberia,it cant even take 1/10th of Siberia because it will never get to it,Siberia and the Far East are two separate regions,and both are larger than the entirety of Japanese holdings in mainland Asia combined.