So was Lenin, but even Lenin produced the NEP. Remember that Kosygin, close to Khrushchev, tried to implement some capitalistic reforms. These didn't include a transition to privatization, but Khrushchev himself encouraged more private plot farming and it isn't unfathomable to imagine some degree of liberalization provided the right conditions.
Besides, the point is to provide a somewhat feasible route for the USSR to win. If they don't reform their economy, they're doomed to fail.
Well, GDP averaged an annualized 5.5% growth during Khrushchev's reign. The system was still full of problems, but the point of this alternate universe is that the USSR is able to by and large fix many of them so far as they could have been fixed.
Story isn't over yet. >.>
That 5.5% can't be called a sustainable rate. That's the rate of taking existing technology and applying it to converting a primarily agricultural economy to a primarily industrial economy. Once full industrialization is achieved, they kind of rate cannot be sustained.
How is it not over? The USSR has ceased to exist. Russia doesn't have it in them to be a new USSR. China is a different scenario.