I suppose one could also fairly argue that victory was assured on December 7, 1941.
The might of the United States industrial capacity and American military leadership and fighting spirit was going to overwhelm those of Germany and Japan. Even the Japanese Admiral Yamamoto, who had been educated and spent time in the USA said after Pearl Harbor, “I fear all we have done is to awaken a sleeping giant and fill him with a terrible resolve.”
The only two Armies that were totally motorized were the Americans and the British. The Russians were probably less motored than the Germans.
Very overstated, Germany was acquiring a lot of potential war material production up through 1942. That much of this went either unutilized or under utilized says much about the ability of the Nazis to co-opt others. There were factories in France that went from making ammunition for French weapons in 1939 to making ammo for German weapons in 1941, and in 1945 were making ammo for American weapons.
Another important if often under appreciated factor in the stalling of the allied offensive near the Franco-German border was that the allies had out-stripped their supply lines, the weather had gotten unfavorable, and the Germans had re-organized and re-equipped after the Falaise Gap. A lot of Frenchmen spent the fall and winter of 1944-45 repairing and rebuilding the French rail network which along with the reopening of the Atlantic ports improved the allied supply situation.
The question is what if Hitler had managed to neutralize Russia by taking Moscow, and creating havoc within the Soviet Government. The War in the East could have taken decades if that occurred. I think Stalin was on much thinner ice than most think. Had Moscow been taken, he may very well have been deposed, and another “Civil War” broken out between the Russians.