Ehhh--probably not. Molotov takes the helm. And probably holds onto it for a long, long time. (How long, you ask? Let me put it to you this way--he died in 1986...)
Molotov handles negotiations "Comrade Stalin is too busy directing things on the front to make but a briefest apperance here. So, what do you want to talk about with me then?"
I think that they might notice that Stalin all of a sudden decided to go all incognito.
If Molotov takes the leadership, I don't think he'd live to 1986. Being the leader of the USSR is a lot more stressful than living in retired obscurity like he did for the last 25 or so years of his OTL life.