So I can explain the role of the state for marxists. The state exists as a means for one class to oppress another. In the dictatorship of the bourgeoisie, the proletariat class is oppressed. In the dictatorship of the proletariat it is the other way around. So as a result of a prolonged dictatorship of the proletariat, you will no longer have a bourgeois class, so the state will 'wither away' because there is no more class to oppress. The dissolution of the state comes with the dissolution of the classes.
To me, a social state doesn't have the same un-resolvable contradictions (needed to create a revolutionary moment) as capitalist states do.
What you are describing is similar to the events of the Cultural Revolution in China, so I recommend reading up on that.
i am the person who says question mark out loud