I having a feeling both Gorbachev and Putin would go bye bye with a longer Stalin. That or eventually some young idealistic Commies would forcibly oust the Old Man in the Kremlin.He was born in 1878. So this raises the possibility of Kennedy having to face Stalin in a Cuban missile crisis (assuming Stalin sends missiles to Cuba).
That sounds pretty frightening , but WW3 didn't kick off during the Berlin airlift, when Stalin was in charge, there's no need for it to start over Cuba.
But even so, the butterflies of Stalin staying in power longer are immense. If there were more purges, would people like Gorbachev , Putin or even Roman Abramovich (owner of Chelsea Football Club) survive ?
The task here is to have Stalin live as long as possible. He does not have to be in charge of the Soviet Union the entire time, but he has to live into his klate 80's or 90's.
What effect does this have on the world?
I would suspect not much difference. He was in his mid-70s when he died - even older than McCain! If he lived longer, even if you don't have him have a stroke, he's probably not going to have the vitality needed to hold onto power. You can be old and senile like Reagan if you're president of the USA, but if you're a vicious Soviet autocrat, you need to watch your back.
Although I guess if he lived longer it could have an effect on the succession.