*sighs*
No, not really.
See, the thing about that famous speech is--yeah, it criticized Stalin. It also criticized Trotsky. And pretty much every member of the Politboro whose name didn't start with 'L', end with 'N', and have three letters in between it. In fact, Stalin actually got off pretty lightly in it. So, no, reading it probably wouldn't have eradicated Stalin's heavily entrenched powerbase. That stated, yes, Stalin was challengable at this time. But it would take a united front from a group of people who spent a great deal of time IOTL demonstrating that they all hated each other.