Here I'd just like to add one thing from the recent second volume of Stephen Kotkin's Stalin biography to give some idea of how close a call Khrushchev had: "Khrushchev was more of a “Trotskyite” than myriad officials who were destroyed for it. If Stalin had suddenly changed his mind, nothing Khrushchev did, or did not do, could have saved his life. Of the thirty-eight highest officials in the Moscow provincial party organization, three survived, two of whom were Kaganovich and Khrushchev..." https://books.google.com/books?id=hMUPDgAAQBAJ&pg=PA520