Ooooh, what about the eventual "whithering away of the state" under the genuinely socialist regime which is supposed to follow the dictatorship of the proleteriat, you naughty Marxist, you? Go to the back of dialectical materialism class and write out Das Kapital 100 times!
Putting aside the fact that this is more a question of historical materialism than dielectical, your point is a bit irrelevant. The state that "whithers away" can only be a workers state, a state that enforces the rule of the majority labouring classes until eventually there are no classes, everyone works, everyone collectively owns the means of production, distribution and exchange.
With no class contentions that state then, as you say, "whithers away". No state in a class based society is going to do that though you silly sausage.
Have another read of "The State and Revolution for Dummies" and do more than just laugh at the pictures of men with funny beards this time.