Like you said, simply impossible..... In fact, probably more on Hilters side then Stalin's at this juncture.
But..........
I would imagine that the Lend lease would cease to exist ( as minimal as it was at this time 42' ) along with any possibility of good realations with the West. Stalin would then take this opportunity to reinforce and modernize his war machine and wait it out for the rest of the world to bleed dry and then liberate eveyone by painting the European continent RED. As this was his initial plan as pointed out by many.
